[. I  BRAKY    OF    'l'\\V. 


University  of  California. 


DiOLOGY 


C 1 R  C  I  'I.  A  TING     />'  K  A  XC/f. 


rn  in  t»«  wee>5  ;  or  a  week  before  the  end  of  the  term, 


PHYSIOLOGY 


AND 


LAWS    OF    HEALTH. 


FOR   THE   USE    OF 


SCHOOLS,   ACADEMIES,   AND    COLLEGES. 


BY  EDWARD   JARVIS,   M.D. 


NEW    YORK: 
A.  S.  BARNES  &  CO.,  51,  53  &  55  JOHN  STREET. 

BOLD   BY  BOOKSELLERS,  GENERALLY,  THROUGHOUT  THE   UNITED   STATES. 


1866. 


BIOLOGY 
LIBRARY 


'Entered,  according  to  Act  of  Congress,  in  the  year  18G5,  by 
EDWARD    JARVIS, 

3F&%* 

In  the  Clerk's  Office  of  the  District  Codrt  of  the  District  of  Massachusetts. 


PREFACE. 


EVERY  human  being  is  appointed  to  take  the  charge  of 
his  own  body.  He  must  supply  its  wants,  direct  its  powers, 
regulate  its  actions,  and  thus  sustain  his  life.  This  respon- 
sibility for  the  care  of  health  takes  precedence  of  all  others, 
and  requires  the  earliest  attention  to  prepare  <o  meet  it. 
Before  any  one  can  have  any  use  for  other  knowledge,  he 
must  know  how  to  live.  He  should,  therefore,  learn  the 
nature  and  the  wants  of  his  frame,  and  of  its  various 
organs,  even  earlier  than  he  studies  the  features  of  the 
earth,  the  science  of  numbers,  or  the  structure  of  language ; 
for,  before  he  can  put  these  to  any  practical  use,  he  must 
eat,  and  breathe,  and  move,  and  think.  Physiology  should, 
then,  be  included  among  the  subjects  of  all  school  educa- 
tion, and  thus  preparation  be  first  made  for  the  fulfilment 
of  the  first  responsibility  of  life. 

The  great  and  sole  object  of  this  work  is  to  teach  the 
laws  of  health,  the  powers  of  the  several  organs,  the  limit 
of  their  strength,  the  way  in  which  they  are  to  be  developed 
and  sustained,  their  proper  uses,  and  the  certain  and  evil 
consequences  that  follow  their  misapplication. 

For  these  purposes,  it  is  necessary  to  learn,  first,  the 
general  structure  of  the  organs  and  parts  which  are  sub- 
mitted to  our  management ;  second,  the  law  of  their  being 


4  PEEFACE. 

and  action  ;  and  third,  their  application  to,  and  connection 
with,  the  common  affairs  of  life. 

The  first  is  limited,  and  is  only  preparatory  to  the  second. 
The  second  also  is  limited,  and  subordinate  to  the  third. 
The  last  is  almost  infinite  in  extent  and  variety,  and  requires 
much  study. 

In  sustaining  the  body  with  food,  and  drink,  and  air,  — 
in  defending  it  with  clothing  and  shelter,  —  in  the  use  of 
our  muscles  and  brain,  —  in  applying  the  body  and  the 
mind  to  whatever  purpose,  we  use  some  or  all  of  our 
organs  ;  and  the  health  and  strength,  or  pain  and  weakness, 
the  good  or  the  evil  consequences,  must  be  in  accordance 
with  the  wisdom  and  faithfulness  with  which  we  govern 
ourselves  in  these  matters.  Therefore  the  knowledge  of 
the  Physiological  Laws,  and  of  their  requirements,  becomes 
of  practical  importance  in  every  moment,  and  in  all  the 
circumstances  of  our  being. 

This  book,  in  a  somewhat  different  form,  was  formerly 
published  under  the  name  of  Practical  Physiology.  But  as 
the  main  purpose  of  the  work  was  to  teach  the  Laws  of 
Health,  and  as  the  whole  of  it  has  been  revised,  and  much 
of  it  re-written,  the  title  is  changed  to  PHYSIOLOGY  AND 
OF  HEALTH,  which  better  describes  the  work. 


EDWAED  JARVIS. 
DORCHESTER,  MASS.,  September,  18C5. 


CONTENTS. 


PART  I. 

DIGESTION  AND  FOOD. 

Chap.  Paga. 

1.  Food  supplies  the  Growth  and  the  Changes  of  Particles  of  the 

Body.  —  Digestive  Apparatus. — Mouth 9 

2.  Saliva. —Mastication.  —  Pharynx.  —  (Esophagus.  —  Swallowing.  13 

3.  Stomach. — Gastric  Juice. — Digestion. — Beaumont's  Observations.  18 

4.  Gastric  Juice  flows  during  Eating.  — Measure  of  Food  to  be  eaten. 

—  Hunger 24 

5.  Motions  of  Stomach. — Heat  during  Digestion.  —  Pyloric  Valve.  29 

6.  Time  required  for  Digestion  of  various  Kinds  of  Food 33 

7.  Drink  with  Food  impedes  Digestion.— Effect  of  Bulk  on  Diges- 

tion. — Light  and  heavy  Bread 36 

8.  Chyme.  —  Alimentary  Canal. — Lacteals. — Chyle  differs  with  Food.     39 

9.  Man  selects  his  Food.  —  Healthy  Digestion  comfortable.  —  Hun- 

ger needs  the  Attention  of  the  Brain 4& 

10.  Appetite  affected  by  State  of  Mind  —Not  identical  with  digestive 

Power  orTaste 47 

11.  Great  Eaters. — Hunger  recurs  when  Blood  wants  more  Chyle.— 

Intervals  between  Meals.  — Regular  Hours  of  Eating  best 50 

12.  Breakfast    should  be    before  Labor  or  Exposure.  — "Dinner.  — 

Lunch.  —  Supper,  injurious  if  late 65 

13.  Quantity  of  Food  should  be  larger  for  the  Active  and  Laborious. .     60 

14.  Quantity  of  Food  determined  by  Wants  of  System  and  digestive 

Power.  —  Measured  thus  when  we  eat  slowly.  —  Excessive  Food 
oppressive.  —  Rapid  Eating 64 

15.  Appetite  allowable,  but  not  a  Guide  ;  injurious  if  it  governs  Eating.     68 

16.  Exercise  before  or  after  Eating  impedes  Digestion 74 

17.  Cheerfulness  at  Meals.  —  Consequences  of  Abuse  of  digestive 

Organs 78 

18.  Animal  and  vegetable  Food.  —  Climate  and  Season  should  affect 

Diet 80 

19.  Temperaments  — should  affect  Diet 83 

20.  Food  according  to  Difference  of  Constitution,  Age,  and  Habit ...  87 

21.  Digestibility  and  Nutritiousness  of  Food  not  identical.  —  Condi- 

ments and  Alcohol  exhaust  Sensibility  of  Stomach.  —  No  Rule 

of  Diet  for  all 89 

PART    II. 
CIRCULATION  OF  THE  BLOOD,  AND  NUTRITION. 

1.  Apparatus  of  Circulation.  —  Heart. — Arteries 93 

2   Veins.  —  Capillaries.  —  Pulmonary  Arteries  and  Veins.  —  Double 

Circulation 100 

3.  Power  of  Heart.  —  Valves.  —  Arteries.  —  Quantity  and  Flow  of 
Blood  varies  with  Circumstances,  Exercise,  States  of  Mind,  and 
Feelings 105 


6  CONTENTS. 

4.  Object  of  Eating. —  All  Parts  of  Body  formed  out  of  Blood  — 

Composition  of  Blood  and  Flesh.  —  Atoms  of  Body  enjoy  short 
Life,  and  are  removed. — Absorbents 110 

5.  Nutrients  and  Absorbents,  active  in  Laborer,  who  needs  more 

Food.— Wens  and  Swellings 113 

6.  Young  and  Active  have  new  Atoms  of  Flesh.  —  Old  and  Inactive 

have  old  Atoms. — Unerring  Precision  of  Nutrition 117 


PART  III. 

RESPIRATION. 

1.  Wasted  Particles  carried  out  of  the  Body.  —  Composition  of  Blood 

in  right  Side  of  the  Heart.  —  Chest.  —  Ribs.  —Spine 120 

2.  Movement  of  Ribs.  —  Diaphragm.  —  Inspiration.  —  Expiration.  — 

Size  of  expanded  and  contracted  Chest 123 

3.  Lungs.  —  Organ  of  Voice.  —  Air-Vessels.  —  Coughing.  —  Respi- 

ration     127 

4.  Waste  Particles.  —  Carbon.  —  Air.  —  Oxygen.  — Nitrogen.  —  Car- 

bonic Acid.  —  Blood  absorbs  Oxygen  from  Air  and  gives  Car- 
bonic Acid 132 

5.  Venous  changed  to  arterial  Blood.  —  Oxygen  consumed,  and  Car- 

bonic Acid  and  other  Matter  given  out,  in  Respiration.  —  Of- 
fensive Breath 135 

6.  Respired  Air  unfit  to  be  breathed  again.  —  Air  should  have  full 

Proportion  of  Oxygen.  —  Air  loaded  with   Carbonic   Acid  or 
Water  can  take  no  «iore  from  Lungs 138 

7.  More  Oxygen  consumecl,  and  Carbonic  Acid  given  out  in  cold, 

than  warm  Air ;   by  strong  and  cheerful  than  by  consumptive 
and  melancholy  Persons 141 

8.  Lungs  must  have  Room  to  breathe 1 14 

9.  Natural  Shape  of  Chest  most  beautiful.  —  Corresponds  to  Size  of 

Body 147 

10.  Frequency  of  Respiration.  —  Size  of  Chest  and  Quantity  of  Air  in- 

haled, correspond  to  the  Waste  to  be  carried  away ^ 150 

11.  Quantity  of  Air  spoiled  by  Loss  of  Oxygen,  by  Carbonic  Acid  Gas, 

and  Vapor  of  Lungs  and  of  Skin 152 

12.  Want  of  fresh  Air  in  Houses,  Parlors,  Sleeping-Rooms,  Cabins..    154 

13.  Foul  Air  in  Workshops,   Churches,   Public  Halls  and  School- 

houses.  —  Ventilation 157 

14.  Connection  between  Fulness  of  Life  and  Respiration  — 162 

15.  Breathing  foul  Air  creates  Weariness,  depreciates  Life,  impairs 

Constitution.  • —  Drowning.  —  Consumption . .    165 

16.  Privation  of  Air.  —  Supply  of  Air  for  all  Animals.  —  Plants  give 

Oxygen,  and  consume  Carbonic  Acid  Gas li>8 


PART  IV. 

ANIMAL  HEAT. 

1.  Animal  Heat  not  changed  by  Temperature  of  surrounding  Matter. 

—  Blagden's  Experiments 171 

2  Animal  Heat  generated  within.  —  Warm  and  cold  blooded  Ani- 

mals. —  Animal  Heat  connected  with  Respiration 174 

3  Latent  and  sensible  Heat.  —  Internal  Combustion 177 

4.   Animal  Heat  increased  by  Exercise.  —  Dependent  on  good  Air 

and  Food.  — Well-fed  warmer   than  ill-fed.— Effects  of  Diet 
and  Alcohol  on  internal  Heat. ..............................    18Q 


CONTENTS. 


Effects  of  Disease,  F^/fgue,  Age,  Sleep,  on  Heat.  — Amount  of 
Heat  prepared  in  a  Day.  —  More  in  warm  than  cold  Seasons. 
Winter  and  Summer  Constitution 185 


PART  V. 

THE  SKIN. 

1.  Skin,  Cuticle,  thickened  by  Friction. — Blisters.  —  Corns 191 

2.  Cuticle.  —  Nails.  —  Hoof.  —  Horns.  —  Seat  of  Color.  —  True  Skin 

contains  perspiratory  Apparatus 1 

3.  Perspiration,  sensible  and  insensible ;  Quantity 198 

4.  Perspiration  affected  by  State  of  Air.  —  Oily  Excretion  of  Skin.  — 

Effect  of  tight  Clothing 201 

6.   Connection  between  Skin  and  Stomach,  Lungs  and  Muscles.— 

Effect  of  Cold 204 

6.  Skin  absorbs  Food,  Liquids,  Medicine,  Contagion,  Poison 207 

7.  Sense  of  Touch ;  impaired  if  Skin  is  foul ;  acute  in  the  Blind ....  210 

8.  Skin  regulates  Heat  by  Perspiration.  —  Sensation  of  Cold  and 

Heat.. I 213 

9.  Quantity  of  Clothing  affected  by  Habit 216 

10.  Clothing,  Need  of,  affected  by  Food,  Digestion,  Health,  Air,  Hab- 

its, Age 220 

11.  Clothing  should  be  loose.  —  Linen,  Cotton,  Silk,  Wool 224 

12.  Flannel. — Cutaneous  Excretions. — Foul  Clothing.  —  Airing  Cloth- 

ing and  Beds 226 

13.  Bathing  makes  Skin  soft  and  healthy 230 

14.  Cold  Bathing.  —  Laborers  need  Bath 233 

15.  Effects  of  Cold  Bathing  on  Health.  —  Time  and  Conditions  of 

Bathing 235 

16.  Sense  of  Touch  made  more  acute  by  Bathing  and  Friction 238 


PART  VI. 

BONES,  MUSCLES,  EXERCISE,  AND  BEST. 

1.  Bones,  Composition  of,  in  Childhood ;  in  Old  Age ;  have  Blood-' 

Vessels  and  Nerves;   subject  to  Growth  and  Decay;    grow 
strong  by  Use 241 

2.  Skeleton.  —  Bones.  —  Head.  —  Chest.  —  Spine.  —  Pelvis 245 

3.  Arms.  —  Wrist.  —  Hand.  —  Leg.  —  Foot.  —  Arch.  —  Shape 250 

4.  Joints.  —  Elbow.  —  Knee.  —  Shoulder.  —  Hip.  —  Structure.  —  Lig- 

aments. —  Sprains.  —  Dislocations 255 

5.  Muscles,  Number,  Action,  Description,  Use 260 

6.  Muscles,  Shape,  Attachments,  Arrangement,  Action 268 

7.  Muscles,  Situation,  sacrifice  Power,  Cooperation 274 

8.  Muscles,  Strength  increased  by  Exercise 278 

9.  Muscular   Strength  unequal;  Action   increases   Power  in   other 

Organs : 282 

10.  Muscular  Action  strengthens  Body  and  Mind.  —  Kinds  of  Exer- 

cise  -. 286. 

11.  Exercise  adapted  to  Strength,  Effect  of,  on  Weak  ;  on  Dyspeptics. 

—  Gymnastic  Exercises 289 

12.  Kinds  of  Exercise.  —  Walking.— Exercise  of  Boys;  of  Girls.— 

Effects  of.  —  Habits  of  English  and  American  Women.  —  Time 

for  Exercise 292 

13.  Exercise,  Place  for.  —  Should  be  regular.  —Needed  by  All 295 

14.  Labor,  Limit  of  Power.  —  Proper  Expenditure  of  Strength 298 


8  CONTENTS. 

t 

15    Effect  of  great  Efforts.—  Proper  Exercise  of  Children  and  Youth.    302 

16.  Laborer    needs    healthy   Organs   of    Digestion,  Nutrition,  Res- 

piration, and  Skin.  —  Connection  of  Exercise  with  Brain. , ....    304 

17.  Effect  of  Hope  and  Confidence,  Doubt  and  Fear,  Cheerfulness 

and  Melancholy,  of  Passion  and  Alcohol,  on  Strength 307 

18.  Attitudes.  —  Spine,  supported  by  Muscles,  very  strong.  — Porters. 

—  Pedlers.  —  Burdens  on  Head.  —  Spine  erect.  —  Centre  of 
Gravity  over  Line  of  Support 309 

19.  Erect  Attitude  best   for  Walking ;   for  Labor ;    for  Mechanics ; 

Farmers.  —  Spine  curved  from  side  to  side  ;  Bent  by  stooping. 

—  Students,  Writers  have  curved  Spine  ;  and  Girls  more  than 
Boys 315 

20.  Time  for  Labor.  —  Experiments.  —  Sleep,  Time  for  ;    Effect  of 

Loss.  —  Disturbed  by  difficult  Digestion 321 


PART  VII. 

BRAIN  AND  NERVOUS  SYSTEM. 

1.  Brain.  —  Nervous  System.  —  Spinal  Cord. — Nerves 325 

2.  Brain  connected  with  all  Parts  by  Nerves;  receives  Impressions 

through  them.  —  Sensations  in  Brain.  —  If  Nerve  is  cut,  Sensa- 
tion and  Power  cease 330 

3.  If  Nerve  is  touched  or  diseased,  Sensation  is  excited  in  the  Brain.   333 

4.  Pain  in  amputated  Limbs. — Voluntary  and  involuntary  Motion.   336 

5.  All  Organs  and  Functions  impaired  when  Brain  is  impaired.  — 

Brain  not  sensitive;  subject  to  Growth  and  Decay;  has  large 
Supply  of  Blood;  fatigued  with  Labor 340 

6.  Day  the  Time  for  mental 'Labor.  —  Brain  gains  Power  by  Exer- 

cise ;  weakened  by  Over- Action  ;  connected  with  other  Organs 

—  Effect  of  Alcohol 344 

7.  Brain  Seat  of  Mind  and  Affections.  —  Power  of  Mind  limited  by 

Power  of  Brain.  — Mind  impaired  by  Indigestion,  Hunger,  Ex- 
cess of  Food.  —  Cheerfulness  favors  'Respiration,  Digestion,  and 
muscular  Action 349 

8.  Brain  sustains  physical  and  mental  Actions.  —  Mind  works  best 

when  Body  is  easy.  —  Uncomfortable  Sensations  interrupt 
Study 353 

9.  Mental  Action  interrupted  by  moral   Feelings,    Anxiety,  Fear. — 

Proper  and  improper  Motives  for  Study 357 

10.  Various  mental  Bowers  affected  by  Education.  —  Precocious  Chil- 

dren. —  Effect  of  Study  on  Health.  —  111  Health  of  literary  Men.    361 

11.  Inequality  of  Powers  ;  affected  by  Education 364 

12.  Habitual  Actions  easy.  —  Perfect  Education.  —  Concentration  of 

Mind.  —  Vacations 368 

13.  If  Inequality  of  Powers  be  disregarded,  Mind  may  be  deranged. 

—  Insanity   from  Misuse   of   Mind,    Dyspepsia,     Cold,    Over- 
Action 373 

14.  Insanity    from   misdirected   Education,  religious   Anxiety,  per- 

verse Habits 375 

15.  Day-Dreaming,  Passion,  Intoxication,  Fright  may  cause  Insanity. 

—  Various  Grades  of  mental  Health.  —  Sound  Mind  in  sound 
Body 377 

16.  Eye.  —  Composition.  —  Tumors.  —  Pupil. —  Effect  of   Light. — 

Tears.... 380 

17-  Near-sightedness.  —  Spectacles.  —  Far-sightedness.  —  Diseases  of 

the  Eye.  — Use  and  Care  of  the  Eye 385 

18.  Ear.  —  Structure.  —  Hearing.  —  Deafness 387 

C inclusion 391 


PHYSIOLOGY   AND    HEALTH. 


PART   I. 

DIGESTION  AND  FOOD. 


CHAPTER  I. 

Growth  of  the  animal  Body,  and  the  Changes  of  its  Particles  supplied 
by  Food.  —  Food  converted  into  Flesh  by  the  Digestive  Apparatus 
and  the  Blood- Vessels.  —  Digestive  Apparatus.  —  Mouth.  —  Teeth. 

1.  THE  animal  body  increases  in  size  and  weight  from 
birth  to  manhood.     The  chief  material  which  supplies  this 
growth  is  the  food  we  eat.    Beside  this,  there  is  another  de- 
mand for  food.     During  the  whole  of  life,  there  is  an  inces- 
sant change  going  on  in  the  particles  that  compose  the  body. 
It  is  a  law  established  by  the  Creator   from  the  beginning, 
that  life  cannot  continue  long  in  animal  matter.     The  atoms, 
which  compose  the  living  body,  receive  the  principle  of  life 
when  they  enter  their  appointed  places,  and  become  apart  of 
the  animal  frame.     They  retain  this  principle  but  a  short 
period,  and,  while  they  retain  it,  they  perform  their  part  of  the 
work  of  life.     But  soon  their  work  is  finished,  and  then  they 
yield  their  vitality,  and  give  up  their  places  to  other  atoms, 
that  come  to  enjoy  life,  and  work  a  while,  and  yield  and  de- 
part, as  those  that  went  before  them  had  done. 

2.  This  law  of  unceasing  change  is  impressed  upon  all 
animal  beings.     In  all,  the  particles  are  constantly  going  out 
through  the  skin  and  the  lungs,  and  an  equal  quantity  of 
matter  must,  therefore,  be  coming' in  through  the  mouth.     If 


10  PHYSIOLOGY    AND   HEALTH. 

this  be  not  done,  and  the  supply  be  unequal  to  the  waste,  the 
animal  loses  flesh,  and  the  body  diminishes  in  weight.  This 
change  of  particles  and  waste  of  matter  differ  in  different 
persons,  and  in  different  circumstances,  as  will  be  shown  in 
the  course  of  this  book. 

3.  Here  is  a  double  necessity  for  the  addition  of  matter  to 
the  body  from  without  —  the  growth  or  increase  of  the  animal 
body  in  its  earlier  years,  and  the  waste  consequent  upon  the 
changes  of  the  particles  through  the  whole  period  of  exist- 
ence.    The  food  supplies  both  these  demands,  and  is  there- 
fore necessary  from  the  beginning  to  the  end  of  life. 

4.  Food   is  not  living   flesh:  much  that  we  eat  —  bread, 
vegetables,    fruit  —  has    not   even   any    resemblance,    in   its 
appearance  or  character,  to  flesh.     Yet  these  matters  —  the 
vegetables  and  the  lifeless  meats  —  are  converted  into  living 
flesh;  and  not  only  so,  but  into  many  and  various  kinds  of 
flesh,  as  many  and  as  various  as  enter  into  the  composition  of 
the  human  body.     All  this  is  done  in  part  by'the  digestive 
apparatus,  and  in  part  by  the  blood-vessels. 

5.  The  digestive  apparatus  effects  the  first  change  in  the 
food ;  it  grinds  it  in  the  mouth,  dissolves  it  and  converts  it  in 
the  stomach   into  a  pulpy  material  fit  to  supply  the  wants  of 
the  blood,   and  sends  the  nutritious  portions  to  the  heart. 
The  blood-vessels  carry  this  blood  to  all  the  portions  of  the 
body,  and  with  this  they  supply  the  growth  and  the  waste  of 
all  the  organs  and  textures. 

0.  This  apparatus  consists  of  the  mouth  and  pharynx,  the 
(Esophagus  or  gullet,  the  stomach,  and  the  intestinal  canal. 
In  the  mouth  are  the  lips,  the  teeth,  the  tongue,  and  the  sali- 
vary glands.  The  pharynx  lies  back  of  the  palate,  between 
the  mouth  and  the  gullet.  The  oesophagus  is  a  tube,  that 
connects  the  mouth  with  the  stomach.  The  stomach  is  a 
large  sack,  in  which  the  digestive  process  is  mostly  performed. 
From  the  alimentary  canal,  the  lacteals  or  absorbent  vessels 
open.  These  take  up  the  nutritious  portion  of  the  digested 
food,  and  carry  it  to  the  veins.  Beside  these  organs,  there 
are  some  others,  such  as  the  liver  and  the  pancreas,  which 


DIGESTION    AND    FOOD.  11 

render  some  assistance  in  the  work  of  digestion.  All  these 
organs  together  form  the  digestive  apparatus,  which  is  com- 
plete and  perfect  in  itself;  nothing  is  wanting  for  the  work, 
and  there  is  nothing  unnecessary.  Each  one  of  these  organs, 
or  parts  of  organs,  has  a  separate  and  distinct  part  to  perform 
in  the  work  of  converting  food  into  the  nutriment  of  the  blood. 

7.  The  mouth  is  the  first  and  only  visible  organ  of  digestion, 
and  first  receives  the  food  from  our  hands  and  our  tables.     It 
is  composed  of  several  parts,  all  of  which  are  employed  in 
the  preparatory  work  of  digestion.     The  lips  and  the  cheeks 
form  the  outward  walls  of  the  mouth,  and  retain  the  food 
after  it  is  received.     The  teeth  serve  to  divide  and  break 
down  the  morsel  to  a  fineness  suitable  to  the  stomach.     The 
tongue  rolls  the  morsel  about,  and  keeps  it  in  its  place  be- 
tween the  teeth,  while  it  is  undergoing  the  process  of  masti- 
cation or  chewing,  and  afterwards  helpst  to  propel  it  back- 
ward in  the  act  of  swallowing. 

8.  The  teeth  differ  in  various  animals,  according  to  the  food 
which  they  eat.     The  carnivorous  or  flesh-eating  animals 
have  teeth  fined  for  seizing  upon  their  prey,  and  for  cutting 
up    fiesh.     Hence  they   have  sharp  cutting  or  front  teeth ; 
arid  long,  sharp  and  pointed  canine  or  stomach  and  eye  teeth  ; 
and  grinders,  with  high  and  sharpened  points,  by  which  they 
chew  or*  masticate  their  fleshy  food  with   facility. 

9.  The    vegetable-eating  animals   have  short,  blunt,   arid 
strong  front  or  incisor  teeth,  by  which  they  break  off  their 
food,  either  grass  or  foliage.     As  they  seize  no  prey,  they 
have  no  use  for  the  sharp  canine  or  stomach  and  eye  teeth ; 
therefore  these  teeth  are  very  small,   and   in  some  scarcely 
seen  ;   but  their  molar  or  grinding  teeth  are  very  large,  brocd, 
and  flat.     Their  surface  is  covered  with  slightly-raised  lines, 
to  enable  them  to  grind  down  their  food,  which  requires  more 
crushing  than  cutting. 

10.  Man  is  neither    herbivorous    nor   carnivorous  exclu- 
sively, but  is  either  or  both,  as  occasion  requires.     Com- 
monly he  is  both.     His  food,  for  the  most  part,  is  a  mixture 
of  vegetables  and  flesh.     He  is  therefore  fitted  with  a  set  of 


I"*  PHYSIOLOGY    AND    HEALTH. 

teeth  partaking  of  the  nature  of  each  of  these  classes.  He 
has  sharp  incisor  teeth,  but  they  are  not  so  long  and  pointed 
as  those  of  the  dog.  His  grinders  are  not  covered  with  points 
as  prominent  and  sharp  as  those  of  the  lion,  nor  are  they  so 
flat  on  the  surface  as  those  of  the  ox;  yet  they  partake  some- 
what of  the  character  of  both.  He  can  chew  either  meat  or 
grains,  as  he  may  desire. 

FIG.  L     Teeth  of  one  Side. 


11.  Man  has  sixteen  teeth  in  each  jaw.     The  four  incisor 
teeth  (Fig.  I.  a,  a)  stand  in  front ;  these  are  broad,  flat,  and 
somewhat  sharp  :  with  these  he  can  bite  or  cut  off  his  morsel 
of  bread,  meat,  &c.     Next  to  these  are  the  canine  teeth, 
(Fig.  I.  6,)  one  on  each  side  ;  these  are  commonly  called  the 
stomach  teeth  in  the  lower  jaw,  and  eye  teeth  in  the  upper 
jaw.     Next  to  these  are  the  bicuspid  teeth,  (Fig.  I.  c,  c,)  two 
on  each  side,  with  two  fangs ;    and  behind   these    are   the 
molar  teeth,  (Fig.  I. d,  d,  d,  e,  e,  e,)  or  grinders,  three  on  each 
side:  these  have  three  fangs,  as  shown  in  Fig.  I.,  in  the 
upper  jaw,  d,  d,  d,  and  only  two  in  the  lower  jaw,   e,  e,  e. 
These  have  pointed  elevations  sufficiently  sharp  to  cut  off 
meat,  and  sufficiently  flat  to  grind  vegetables  and  grains. 

12.  The  teeth  are  firmly  set  in  each  jaw,  with  long  fangs, 


13 

, 

so  that  they  are  not  easily  started  rnmr  Ilium  places.  They 
are  composed  of  soft  bone  within,  but  are  covered  on  the 
outside  with  an  enamel  of  very  hard  texture,  which  admits 
of  an  exquisitely  fine  polish.  This  enamel  comes  in  contact 
with  the  food,  the  drinks,  and  the  air.  It  will  bear  great  variety 
of  exposure,  and  resist  the  wear  of  great  friction.  Yet,  when 
the  mouth  is  neglected,  the  enamel  is  apt  to  decay.  If  any 
of  the  food,  which  has  been  masticated  and  mixed  with  the 
saliva,  be  suffered  to  remain  about  the  teeth,  this  mixture 
undergoes  a  corrupting  fermentation,  and  acts  upon  the  hard 
enamel.  After  a  while,  a  hole  is  eaten  through  this  cover- 
ing; and  then,  when  this  decay  reaches  the  softer  sub- 
stance of  the  body  of  the  teeth,  it  acts  much  more  rapidly. 

13.  This  decay  is  assisted  also  by   the  gathering  of  the 
secretions  of  the  mouth.     The  salts  and  acids  of  the  saliva 
combine  with  the  food,  and  form  tartar,  which  covers  parts 
of  the  teeth  with  a  hard  crust.     This  can  be  easily  prevented 
by  washing  the  teeth  frequently,  and  completely  removing 
all  the  food   arid  other  gatherings  of  the  mouth,  after  each 
meal,  and  also  in  the  morning,  after  an  interval  of  sleep. 

14.  The  teeth  have   blood-vessels  and   nerves;    they  are 
endowed  with  life ;    and,  as  most  people  have  occasion  to 
know,  they  also  have  an  exquisite  sensibility.     When  they 
are  sound,  they  seem  to  have  little  or  no  sensation  ;  but  when 
they  are  decayed,  and  exposed  to  extremes  of  temperature,  to 
very  hot  or  very  cold  matters,  or  even  to  the  air,  they  suffer 
acute  pain. 


CHAPTER   II. 

Salivary  Glands.  —  Flow  of  Saliva.  —  Mastication  necessary. — Ef- 
fect of  imperfect  Mastication.  —  Pharynx.  —  (Esophagus.  —  Epi- 
glottis. —  Swallowing. 

15.  THE  teeth  can  only   grind  the  food  to  powder.     In 
this  condition,  it  can  neither  be  swallowed,  nor  is  it  fit  for  the 


14 


PHYSIOLOGY    AND    HEALTH. 


next  stage  of  the  process  of  dige'st'on  in  the  stomach.  It 
must  be  not  only  crushed  and  divided,  but  it  must  be  mois- 
tened and  reduced  to  a  pulpy  consistence.  For  the  purpose 
of  supplying  the  necessary  moisture,  there  is  provided  in  the 
mouth  a  set  of  glands,  which  prepare  and  throw  out  the 
saliva  or  spittle,  sufficient,  in  time  of  health,  to  moisten  and 
soften  all  the  food.  These  little  glands  are  placed  in  the 

FIG.  II.    Salivary  Glands. 


cheeks,  (Fig.  II.  «,)  and  under  the  tongue,  (Fig.  II.  &,)  and 
under  the  jaws,  (Fig.  II.  c,)  and  open,  through  very  minute 
tubes  and  apertures,  into  the  mouth,  (Fig.  II.  d,d.)  When  the 
cheeks  and  tongue  are  still,  these  glands  are . inactive,  and 
throw-out  no  more  liquid  than  enough  to  keep  the  mouth  moist. 
The  presence  of  any  matter  in  the  mouth,  the  chewing  of  our 
food,  tobacco,  &/c.,  and  any  motion  of  the  jaws,  cheeks,  or 
tongue,  excite  these  glands,  and  induce  the  flow  of  their 
fluids.  All  these  motions  are  entirely  needless,  except  when 
we  are  eating  or  talking.  They  are  under  our  control,  and 
consequently  the  flow  of  saliva  is  under  our  command.  If, 
then,  we  use  the  mouth  only  for  its  intended  purposes  of 
eating  arid  conversation,  it  will  be  always  moist,  but  never 
full  of  saliva ;  and  then  we  should  have  no  occasion  to  in- 
dulge in  the  unnatural  and  offensive  habit  of  spitting. 


DIGESTION    AND    FOOD.  15 

16.  The  saliva  flows,  during  the  process  of  mastication,  in 
some  measure  proportionate  to  the  dryness  of  the  food.     The 
salivary  glands  have  a  very  active  sympathy  with  the  appe- 
tite, and  will  sometimes  send  forth  a  flow  of  saliva  at  the 
mere  presence  of  savory  food,  so  that  the  common  saying, 
that  "  one's   mouth  waters"  at  the  sight  of  agreeable  dishes, 
is  physiologically  true.     These  glands  are  important  assist- 
ants in  the  masticating  process,  when  they  and  the  body  are 
in  health  ;  but  in  fevers,  and  in  some  other  diseases,  these 
organs  refuse  to  act,  and  the  mouth  then  is  dry  and  parched. 

17.  By  the  united  operation  of  the  teeth  and  the  salivary 
glands,  the  food  is  first  ground  into  small  particles,  and  then 
made  into  a  soft  pulp,  in  the  mouth.     Both  these  operations 
are  necessary,  for  "we  cannot  swallow  the  morsels  unless  they 
are  divided  and    moistened,  either    naturally  or  artificially. 
Let  any  one  attempt  to  swallow  a  mouthfuj  of  dry  bread 
without   chewing,  or  powdere4  cracker,   without  saliva  or 
other  fluid  to  soften  it,  and  he  will  find,  that  this  process, 
which,  when  proper  preparation  is  made  for  it,  is  one  of  the 
easiest  and  most  agreeable,  is  now  one  of  the  most  difficult 
and  unpleasant.     If  the   food  be  not  divided  while    in    the 
mouth,  it  cannot  be  done  afterwards;  there  is  no  machinery 
nor  power  in  the  stomach  to  effect  this  division. 

18.  In  the  back  part  of  the  mouth  is  a  second  chamber, 
called   the   pliarynx,  separated  from  the   anterior  or   front 
chamber    by   a  movable  curtain,  called  the  palate.      This 
curtain,   hanging    between   these   two    chambers,   is   easily 
seen  when  the  mouth  is  partly  opened,  and  seems  then  to  be 
the  farthest  boundary  of  the  cavity.     But  when  the  mouth  is 
stretched  widely  open,  this  curtain  is  raised,  and  the  other 
chamber  is  disclosed  behind  it.     A  little  knob  or  tongue  of 
flesh  hangs  down  from  the  middle  of  the  palate,  nearly,  and 
sometimes    quite,    to  the  tongue,  and   partially  or   entirely 
divides  the  passage-way  from  the  front  to  the  back  chamber. 
This  gives  the  appearance  of  two  passages,  one  on  the  right 
and  the  other  on  the  left  side. 

19.  Four  passages  open  out  from  the  back  chamber;  one 


16  PHYSIOLOGY    AND    HEALTH. 

leads  forward  to  the  mouth,  the  second  upward  and  forward 
to  the  nose,  the  third  downward  to  the  windpipe  and  lungs, 
and  the  fourth  downward  and  backward  to  the  stomach. 
The  (esophagus,  or  gullet,  that  carries  the  food  and  drink  to 
the  stomach,  opens  from  the  farthest  part  of  the  mouth,  and 
lies  behind  the  windpipe,  next  to  the  back-bone. 

20.  The  windpipe  opens  between  the  tongue  and  the  gullet, 
in  the  front  part  of  the  throat.     It  is  seen  and  felt  in  all  per- 
sons, and  in  some  it  is  very  prominent.     As  the  windpipe 
lies  between  the  tongue  and  the  gullet,  the  food,  going  from 
the  mouth  to  the  stomach,  must  pass  over  it,  and  would  be 
liable  to  fall  in  if  there  were  not  an  effectual  protection  pro- 
vided against  this  accident.     The  windpipe  is  made   of  a 
number  of  stiff  cartilages,  and  its  mouth  is  always  open; 
but  there  is  placed  over  this  mouth  a  little  clapper,  or  valve, 
called  the  epiglottis,  which  is  fixed  by  a  hinge  to  the  front 
edge  toward  the  tongue,  and  opens  toward  the  O3sophagus 
behind. 

21.  This  valve  usually  stands  open  to  allow  the  passage  of 
air  into  and  out  of  the  lungs.     But  it  is  exquisitely  sensitive  ; 
when  it  is  touched  with  any  other  matter,  it  falls  down  at 
once,  and  covers  the  aperture  of  the  windpipe,  and  protects 
it  from  any  intrusion.     Whenever  we  swallow  food  or  drink, 
the  instant  the  morsel  or  the  fluid  reaches  this  valve,  it  falls, 
and  allows  it  to  glide  over  it,  into  the  gullet  behind,  and  then 
it  rises  again  to  give  passage  to  the  air. 

22.  While  we  are  swallowing  we  cannot  breathe ;    if  we 
attempt  to  do  this,  or  to  speak,  or  do  any  thing  which  will 
cause   this  valve  to  open,  some  minute  particle  of  food  or 
drop  of  fluid  may  get  into  the  windpipe,   and  cause  painful 
irritation  and  coughing.     This  is  a  common  accident,  and 
may  be  easily  prevented  by  not  speaking  while  attempting  to 
swallow  food  or  drink.     At  the  same  time  that  the  epiglottis 
falls  to  allow  the  food  to  pass  safely  over  the  windpipe,  the 
soft  palate,  the  curtain  that  hangs  between  the  front  and  the 
back  chamber  of  the  mouth,  is  turned  backward   and  up- 
ward, and  covers  the  passage-way  that  leads  to  the  nostrils, 
and  defends  them  from  the  ingress  of  the  food. 


DIGESTION    AND    FOOD. 


17 


FIG.  III. 

Section   of  the 

(Esophagus. 


a,    Muscular 
fibres,  running 
lengthwise. 
Circular  fibres. 


23.  The  pharynx  connects  the  mouth  with 
the  oesophagus.     It  spreads  out  like  a  tun- 
nel behind  the  palate,  and  is  open  to  receive 
the  food.     The  oesophagus  extends  from  the 
pharynx  to  the  stomach.     It  is  a  soft  tube, 
about  nine  inches  long,  and  rather  less  than 
an  inch  in  diameter.    It  is  covered  with  two 
layers  of  muscular  fibres,  one  of  which  runs 
lengthwise,  (Fig.  III.  a,  «,)  the  other  winds 
around  it  successively  from  top  to  bottom. 
(Fig.  III.  b.)    These  muscles  have  a  power 
of  contraction,  or  of  drawing  themselves  up, 
like  the  earth-worm,  and  again  of  relaxing 
themselves,  and  being  stretched  out  loosely. 
They  draw  around  the  gullet  like  the  string  a> 
of  a  work-bag,  and  thus,  narrowing  the  pas- 
sage, force  onward  whatever  food  or  other  $f 
matter  there  is  within  it. 

24.  When  the  food  is  thrust  backward  by  the  tongue,  it 
passes  into  the  pharynx,  which  closes  upon  it,  and  propels  it 
downward  into  the  oesophagus.    Then  the  uppermost  band  of 
muscular  fibres  contracts,  and  closes  its  upper  end,  and 
prevents  a  return  of  the  food  backward.     Then  the  next 
band  contracts,  and  forces  the  food  onward.     Then  the  third 
band  does  the  same.     Thus,  while  each  one  is  successively 
pressing  upon  the  contents  of  the  tube,  these  are  forced  on- 
ward  and  downward  to  the  stomach.     While  one  band  is 
contracting,  that  which  is  next  below  it  relaxes,  to  admit  the 
entrance  of  the  food.     This  is  the  process  of   swallowing, 
and  is  performed  by  the  successive  action  of  these  circular 
muscles.     These  bands  are  so  well  adapted  to  each  other, 
and  work  in  such  harmony,  that  we  are  not  aware  of  the 
steps  of  this  operation.    Vomiting  is  performed  upon  the  same 
principle,  except  that  the  order  of  contraction  is  reversed  ;  the 
lower  fibres  first  contract,  and  then  those  next  above,  and 
thus  their  action  forces  solid  and  fluid  matters  upwards,  from 
the  stomach  to  the  mouth. 


18 


PHYSIOLOGY    AND    HEALTH, 


CHAPTER   III. 

Stomach. —  Gastric  Juice. —  Processes  of  Digestion  seen  by  Dr. 
Beaumont. 


Fia.  IV.  Stomach. 


a.  (Esophagus, 
opening   into    tho 
stomach. 

b.  Pyloric    ori- 
fice, opening  into 
the  alimentary  ca« 
nal. 

r,  c.  Duodenum, 
or  upper  part  of 
the  alimentary  ca- 
nal. 

d.  Left  end  or 
great  pouch. 


25.  THE  stomach(F'ig. IV.)  is  along,  round,  and  somewhat 
irregularly-shaped  sack.  It  is  placed  on  the  left  side  of  the 
abdomen,  just  below  and  within  the  lower  ribs,  and  runs 
crosswise  towards  the  right  side,  (Fig.  V.  f.)  It  has  two 
apertures,  one  towards  the  left  extremity,  (Fig. IV.  a,)  where 
the  gullet  terminates,  and  the  other  on  the  right  extremity, 
(Fig.  IV.  &,)  where  the  stomach  opens  into  the  alimentary 
canal,  (Fig.  IV.  c,  c.)  This  organ  is  very  expansive,  and  varies 
greatly  in  size,  according  to  the  quantity  of  matter  contained 
in  it.  It  is  sometimes  so  much  distended  with  a  large  meal, 
or  with  liquid  or  gas,  as  to  hold  two  quarts  or  more;  at 
other  times  it  is  so  contracted  as  to  contain  less  than  a  pint. 
It  usually  contracts  down  to  its  contents,  however  small ; 
and  is  therefore  always  full,  either  of  solid  or  fluid  matters 
or  of  gas. 


DIGESTION    AN 


FIG.  V.    Relative  Position  of  the  Organs  of  Digestion  and 
Respiration. 


a.  Right  lung. 
&.  Left  lung. 

c.  Heart. 

d.  Diaphragm. 

e.  Liver. 

/.  Stomach. 

g.  Front    wall    of 
the  abdomen. 

h.  Windpipe. 


26.  The  average  size  of  the  stomach  differs  with  the 
habits  of  men  and  the  kind  of  food  which  they  consume. 
It  is  larger  in  those  who  live  on  vegetable  focd,  which  con- 
tains less  nutriment  in  the  same  bulk,  than  in  those  who  .live 
on  animal  food,  which  is  richer  and  more  nutritious,  and 
therefore  occupies  less  space.  This  difference  is  more 
marked  between  the  size  of  the  stomach  of  the  carnivorous, 
or  flesh-eating  animals,  and  that  of  the  herbivorous,  or  vege- 
table-eating animals.  The  hare  has  a  much  larger  stomach 
than  the  greyhound.  The  stomach  of  the  cow  is  large,  and 
her  alimentary  canal  is  twenty-four  times  the  length  of  her 
body ;  whereas,  in  some  of  the  carnivorous  animals,  this 
canal  is  not  much  longer  than  their  bodies  are.  Men  who 
are  in  the  habit  of  gormandizing  have  very  great  stomachs. 


20  PHYSIOLOGY    AND    HEALTH. 

and  these  are  daily  stretched  to  such  an  extent  as  would  be 
very  painful,  and  even  injurious,  to  more  temperate  eaters. 

FIG.  VI.     Inside  and  Coats  of  the  Stomach. 


a,  Mucous  coat, 
6,  Its  edge. 

c,  Edge  of  the  mus- 
cular coat. 

d,  Peritoneal  coat. 

e,  (Esophagus. 
/,  Its  opening. 

Pyloric  orifice. 
ht  Right  end. 
t,  Left  end. 


27.  The  texture  of  the  stomach  is  fleshy,  and  very  soft  and 
flexible.     Its  thickness  varies  according  to  the  quantity  of  its 
contents.     It  is  thinner  when  it  is  expanded  and  its  sides  are 
stretched   than   when   it   is   contracted    and    its    sides    are 
shrunken.     It  is  composed  of  three  coats,  or  layers.     The 
outer  or  peritoneal  coat  (Fig.  VI.  d)  is  a  part  of  that  covering, 
which  wraps  about  all  the  contents  of  the  abdomen,    and 
forms  the  outer  coat  of  the  whole  alimentary  canal,  and  lines 
the  walls  of  this  cavity.     It  is  very   tough  and  strong,  and 
being  attached  to  the  back-bone  and  the  sides  of  the  abdo- 
men, it  holds  with  sufficient  firmness  all  the  inner  organs, 
which  it  covers,  and  sustains  them  in   their  places ;  and  yet 
it  is  attached  in  such  a   manner  as  to  allow  the  expansions 
and  motions  of  the  stomach  and  of  the  canal. 

28.  The  middle  is  the  muscular  coat,  (Fig.  VI.  c.)  It  has  two 
layers  of  fleshy  fibres,  or  strings,  which  run  crosswise  of  each 
other  at  right  angles.     One  of  these  layers  runs  lengthwise 
from  one  end  of  the  stomach  to  the  other.     The  other  layer 
surrounds  the  sack ;   and  winding  in  successive  circles  from 
end  to  end  of  the  organ,  it  covers  the  whole  as  a  similar  layer 
of  fibres  covers  the  gullet.     This  muscular   coat  has  a  cor* 


DIGESTION    AND    FOOD.  21 

tractile  power,  and  when  it  draws  itself  down,  it  diminishes 
the  capacity  of  the  stomach  so  as  to  press  upon  its  contents, 
however  small  they  may  be;  and  again,  it  expands  so  as  to 
allow  the  sack  to  be  enlarged  for  the  reception  of  whatever 
food  or  liquid  is  then  thrown  into  it. 

29.  The  inner  or  mucous  coat  (Fig.  VI.  a)  covers  the  inner 
surface  of  the  organ.     It  is  loose,  soft,  spongy,  and  porous. 
It  is  not  elastic,  and  does  not  stretch  and  contract,  when  the 
stomach  is  enlarged  or  diminished.     But  when  the  organ  is 
distended,  this  membrane  is  smooth;  and  when  contracted,  it 
is  drawn  into   folds,  like  the  skin  of  the  palm  of  the  hand, 
or  of  the  inner  side  of  the  joints  of  the  fingers  when  closed, 
or  of  the  outside  when  open. 

30.  The  anatomy  of  these  three  coats  is  somewhat  familiar 
to  most  people  who  have  eaten  tripe,  vvhiclj  is  a  preparation 
of  the  stomach  of  the  ox  or  cow.     The  outer  layer  of  this 
is  a  dense,  tough  covering  of  fatty  matter,  and  comparatively 
strong.     The  next  or  middle  layer  is  composed  of  reddish 
fibres.     These  are  stringy,  and  are  what  is  commonly  called 
the  lean  meat.     This  layer  differs  in  thickness   in   different 
parts  of  the  stomach.     The  inner  layer  is  a  thick,  soft,  fatty 
matter,  and  filled  with  superficial  cells.     The  human  stom- 
ach has  similar  coats,  which  are  arranged  in  the  same  man- 
ner, and  perform  the  same  duties. 

31.  These  three  coats,  or  coverings,  constitute  the  stomach. 
They  have  each  a  distinct  part  to  perform  in  the   digestive 
process,  and  each  one  is  fitted  for  its  peculiar  work,  and  for  no 
other.     The  outer  coat  gives  strength  and  support  to  the 
whole.     The  middle  coat  expands  and  contracts,  to  give  due 
size  to  the  sack;  it  produces  the  motions  in  the  stomach, 
which  agitate  the   food  and  promote  the  work  of  digestion ; 
and  finally  this  coat  presses  the  sack  down  upon  the  contents, 
to  expel  them  when  they  are  digested.     The  inner  or  lining 
coat  exudes  upon  its  own  surface  a  slimy,  mucous  substance, 
which  protects  it  from  the  irritation  of  the  matters  that  are 
put  into  the  organ,  and  also  prepares  the  gastric  juice  —  a 
powerful  fluid  which  dissolves  the  food. 


22  PHYSIOLOGY    AND    HEALTH. 

32.  The  gastric  juice  is  prepared  within  the  walls  of  the 
stomach,  and  thrown  out  from  its  mucous  or  lining  mem- 
brane in  a  manner  similar  to  that  in  which  the  saliva  is 
thrown  out  from  the  glands  of  the  mouth,  or  the  sweat  is 
poured  out  from  the  skin.     It  exerts  a  powerful  action  on 
all  proper  and  natural  sorts  of  food  —  meat,  bread,  vegeta- 
bles, fruits,   mixed  in   every  variety  of  combination,  and 
cooked  in  all  kinds  of  ways.    It  dissolves  certain  important 
elements  which  form  a  constituent  part  of  nearly  all  our 
food.     By  this  process  it  helps  to  reduce  the  finely-divided 
mass  to  a  condition  which  is  fitting  for  the  absorption  of  its 
nutritious  portions  into  the  blood. 

33.  These  elements,  which  are  thus  acted  upon  by  the 
gastric  juice,  are  called  the  albuminoid  portions  of  the  food, 
because  they  resemble  the  albumen  or  white  of  an  egg  in 
their  properties  and  relations.  These  elements  are  combined, 
in  different  forms  and  proportions,  with  other  constituents  of 
the  food,  such  as  the  starch,  sugar,  oily  matters,  salts,  &c., 
and  are  among  the  most  constant  and  nutritious  of  its  ele- 
ments.   Thus,  in  form  of  albumen  cindjibrine,  they  constitute 
the  basis  of  all  our  meats  ;  as  cascine  they  enter  into  milk  ;  as 
gluten  they  exist  in  large  proportions  in  the  grains  —  wheat, 
corn,&,c. ;  while  as  legumine  they  are  found  in  peas  and  beans. 

34.  It  has  been  ever  easy  to  learn  the  structure  of  the 
stomach,  and  the  arrangement  of  its  coats,  and  its  relation 
to  other  organs.     But  the  method  by  which  these  operate, 
and  the  processes  of  digestion,  have  been  left  to  inference  or 
conjecture,  until  within  a  few  years.     Men  could  watch  their 
own  sensations  of  comfort  or  pain,   and  notice  the  results 
of  strengthening  and  weakness  from  eating ;  but  they  could 
not  see  the  steps,  and  had  no  means  of  knowing,  for  a  cer- 
tainty, what  was  going  on  in  the  stomach,  until  an  opportu- 
nity was  offered  to  Dr.  Beaumont,  of  the  United  States  army, 
in  the  year  1822,  and  afterwards.    A  young  soldier,  Alexis  St. 
Martin,  received  a  gun-shot  wound  in  his  left  side,  which  laid 
his  stomach  open.     The  aperture  did  not  close  up,  but  left  an 
opening,  through  which  food  could  be  put  in  and  taken  out, 
and  the  whole  process  of  digestion  observed.     A  flap  of  skin 


DIGESTION    AND    FOOD.  23 

and  flesh  hung  over  this  unnatural  passage-way,  and  closed 
it,  and  retained  the  contents  of  the  stomach.  But  it  could 
be  raised  at  any  time,  and  the  cavity  of  the  stomach  exposed. 

35.  Dr.  Beaumont  took  St.  Martin  into  his  family,   and 
tried  a  great  variety  of  experiments  upon  him,  and  made  re- 
peated observations  in  regard  to  his  digestion,  during  the  year 
1825,  and  from  1829  to  1833.     Dr.  B.  had  thus  an  opportu- 
nity, which  has  been  afforded  to  no  other  man  on  record, 
of  watching  the  processes  of  digestion,  and  observing  every' 
step  as  it  occurred.     St.  Martin  masticated  his  food  in   his 
mouth,   and  swallowed  it  in  the  usual  way.     But  it  could 
be  examined  or  taken  out  through  the  aperture,  at  any  stage 
of  digestion  in  the  stomach.     Food  or  fluids  could  be  put 
into  the  stomach,  gastric  juice  could  be  taken  out,  a  ther- 
mometer passed  in,  and  the  temperature  ascertained. 

36.  St.    Martin   took   the   various  kinds  of  food  usually 
eaten.     These  were  prepared  in  all  the  common    methods 
of  cookery.      Dr.  B.  closely  watched  them   after  they  were 
eaten,  and  noticed    the    changes    as  they  successively  took 
place  in  each  of  the  different  articles  which  had  been  taken. 
He    watched    the   effect   of  every    kind   of  food    upon   the 
stomach,  the  flow  of  the  gastric  juice,  the  action  of  this  fluid 
upon  the  matters  presented  to  it,  and  the  movements  of  the 
sack,     He   observed,    also,  precisely   the   time  required  to 
digest  or  to  change  each  article  into  chyme.    Subsequently 
Professor  Lehmann,  of  Leipsic,  and  other   chemists   and 
physiologists  of  Europe,  and  Dr.  Dalton,  of  New  York, 
and  others  in  this  country,  have  tried  many  experiments, 
and  made  many  observations  on  men  and  animals,  in  order 
to  determine  the  law  of  digestion.    These  philosophers  have 
generally  confirmed  the  opinions  of  Dr.  Beaumont ;  but  they 
have  made  the  farther  discovery,  that  only  parts  of  the  ele- 
ments of  the  food  are  digested  in  the  stomach,  while  the 
others  are  digested  in  the  intestinal  canal  below.     All  of 
these  observers  kept  minute  records  of  their  observations, 
and  have  since  published  the  results. 


24  PHYSIOLOGY    AND    HEALTH. 


CHAPTER   IV. 

Gastric  Juice  secreted  in  the  Stomach  when  Food  is  swallowed  — 
This  Quantity  of  Juice  is  the  Measure  of  the  Food  to  be  eaten.  — 
Hunger.  —  Gastric  Juice  combines  with  Food  when  swallowed, 
if  eaten  slowly. 

37.  BUT  even  these  careful  observers  do  not  explain  the 
mysteries  of  digestive  power  and  action.     They  could  only 
discover  the  steps  by  which  nature  accomplishes  this  won- 
derful transformation  of  dead  food  into  the  nutriment  of  the 
living   blood.     The  food  is   masticated  and  swallowed.     It 
then  is  carried  to  the  left  or  larger  end  of  the  stomach,  and 
there  lodged  in   a  great  pouch.     As  soon    as   the  food    is 
swallowed,  some   gastric  juice,  sufficient  to  moisten   it,    is 
poured  out  from  the  lining  membrane,  and  mingles  with  and 
softens  it.     The  more  completely  the  food  has  been  masti- 
cated,  and  the  more  minutely  it  has  been   divided  in   the 
mouth,  the  more  readily  does  this  gastric  juice  enter  into 
and  combine  with  it.     First  it  mixes  only  with  the  surface 
of  each  broken  portion,  and,  as  fast  as  the  minute  particles 
are  softened  by  this  fluid,  they  are  separated  by  the  continual 
motion  of  the  stomach,  and  then  the  fluid  has  opportunity  to 
mingle  with  other  particles ;  and,  these  being  removed,  still 
other  particles  are  exposed    and  moistened ;    and    thus    the 
work  goes  on,  until  all  the  food  is  wet  and  softened  by  this 
dissolving  fluid. 

38.  The    stomach    is    not    always    full    of  gastric   juice. 
Usually  there  is  none  of  this  fluid  in  it,  except  when  some 
food  or  other  matter  is  there  to  excite  the  lining  membrane 
to  secrete  it  and  pour  it  out.     When  we  put  a  morsel   into 
the  mouth  and  begin  to  move  the  jaws,  the  salivary  glands 
are  stimulated  to  pour  out  saliva  sufficient  to  moisten  it.    In  a 
Bome.what  similar  manner,  the  same  morsel,  when  it  reaches 


DIGESTION    AND    FOOD.  25 

the  stomach,  stimulates  the  mucous  coat  to  throw  out  suf- 
ficient gastric  juice  to  dissolve  it.  In  neither  case  is  fluid 
enough  given  out  at  once  to  mix  with  an  entire  meal.  But 
as  we  see  it  in  the  mouih,  so  in  the  stomach  it  is  given  out, 
part  by  part,  as  often  as  a  portion  of  food  arrives  and  de- 
mands it.  Even  this  small  quantity  is  not  poured  out  with  a 
gush,  but  it  oozes  out  slowly,  as  the  perspiration  oozes  from 
the  forehead,  until  there  be  enough  to  mix  with  the  new 
morsel  that  is  swallowed.  This  is  not  a  rapid  process;  it 
takes  a  few  moments  to  wet  each  morsel.  If,  then,  we  swal- 
low more  rapidly  than  the  morsels  can  be  wet  with  the  juice, 
they  must  accumulate,  and  wait  for  the  fluid  to  come. 

39.  This  secretion  and  flow  of  gastric  juice  commences 
as  soon  as  any  food  reaches  the  stomach,  and  then  continues 
to  flow,  if  stimulation  by  new  morsels  is  successively  repeat- 
ed. But  this  secretion  is  not  without  end.  This  liquid 
cannot,  like  the  saliva  in  the  mouth,  be  made  to  flow  as  long 
as  we  wish.  There  is  a  limit  to  the  gastric  juice  which  will 
be  secreted  at  any  one  time.  Dr.  Beaumont  says,  "  When 
the  alimentary  matter  is  received  into  the  stomach,  this  fluid 
then  begins  to  exude  from  its  proper  vessels,  and  increases 
in  proportion  to  the  quantity  of  aliment  naturally  required 
and  received."  *  It  flows,  then,  not  in  proportion  to  the  food 
which  we  may  happen  to  eat,  but  in  proportion  to  the  quan- 
tity of  nutriment  which  the  body  needs.  When,  therefore, 
so  much  of  this  juice  is  poured  out  as  will  dissolve  what  food 
we  need  at  any  one  time,  it  will  stop,  and  the  mucous  mem- 
brane will  give  no  more.  And,  as  only  a  definite  proportion 
of  aliment  can  be  digested  in  a  given  quantity  of  this  fluid, 
if  more  be  eaten  than  this  quantity  can  dissolve,  —  that  is,  if 
more  food  be  swallowed  than  the  body  needs  to  supply  its 
waste,  —  the  excess  either  remains  in  the  stomach  undigested, 
and  is  there  a  cause  of  intense  pain  and  oppression,  or  it  is 
thrown  out  and  onward,  in  a  crude  state,  to  disturb  the 
organs  beyond. 

*  Observations,  p.  85. 
3 


26  PHYSIOLOGY    AND    HEALTH. 

40.  Knowing,  then,  that  the  stomach  can   give  out  only 
a  limited  quantity  of  gastric  juice  at  any  one  time,  and  that 
this  fluid  can  dissolve  only  a  limited  quantity  of  food,  and 
also  that  this  corresponds  with  the  wants  of  nutriment  in  the 
body,  we  have  a  measure  of  the  amount  of  food  which  should 
be  taken  at  each  meal;  that  is,  as  much  as  the  gastric  juice 
can  combine  with  in  the  stomach  and  digest.     This  is  seem- 
ingly unknown,  and  therefore  no  guide  for  us.     But  it  can 
be  ascertained  by  watching  the  effects  of  eating.    There  is 
an  apparent  understanding  between  the  general  system  and 
the  healthy  digestive  organs ;  at  least,  there  is  such  a  sym- 
pathy between  them  that,  when  the  one  wants  nourishment, 
the  other  is  ready  to  digest  it.     This  gives  the  sensation  of 
hunger,  which  appears  to  be  in  the  stomach.     When  this  is 
felt,  the  lining  membrane  is  ready  to  give  forth  the  gastric 
juice  to  digest  the  food ;  and,  as  long  as  the  hungry  feeling 
continues,  this  fluid  may  flow.     But  when  this  ceases,  there 
is  no  more  need  of  food,  no  more  sensation  of  want,  and  no 
more  digestive  power  than  sufficient  to  dissolve  what  has 
been  already  eaten.     Then  there  is  a  feeling  of  satisfaction 
and  ease  in  the  stomach,  for  the  appetite  and  craving  are 
gone. 

41.  We  can  make  use  of  this  guide  to  the  proper  quantity 
of  food,  and  measure  it  by  the  quantity  of  gastric  juice  which 
can  be  supplied  at  one  time,  only  when  we  eat  slowly,  when 
the  morsels  which  we  swallow,  and  the  fluid  which  is  to  dis- 
solve them,  keep  pace  with  each  other,  and  meet  together  in 
the  stomach.     By  this  cautious  proceeding,  we   adapt  the 
supply  of  food  exactly  to  the  wants  of  the  body,  and  stop  as 
soon  as  this  want  ceases.     But  if  we  eat  more  rapidly  than 
this,  and  continue  to  eat  at  this  rate  as  long  as  the  gastric 
juice   continues   to   be   secreted,  the    food   gathers    in    the 
stomach  faster  than  the  digesting  fluid.     There  is  an  accumu- 
lation of  food  waiting  to  be  moistened.     And  when,  finally,  as 
much  of  this  liquid  is  given  out  as  can  be  afforded,  there  is 
still  this  excess  of  food  already  in  the  stomach,  so  much  more 
than  is  needed  or  can  be  digested. 


DIGESTION    AND    FOOD.  27 

42.  Hunger  is  the  sensation  of  want  of  more  nutriment 
in  the  body.     But  this  is  felt,  not  in  the  body  where  nutri- 
ment is  needed,  but  in  the  stomach,  and  there  only  when  that 
organ  is  ready  to  give  out  sufficient  and  proper  gastric  juice 
to  digest  the  food  which  is  required.     There  must  be  a  cor- 
respondence between  the  general  frame  and  the  stomach,  to 
produce  this  feeling  of  hunger.     The  one  must  be  in  need  of 
more  nutriment,  and  the  other  ready  and  able  to  digest  it. 
It  is  not  enough  that  the  body  is  in  want.     If  the  stomach 
cannot  render  aid  in  the  supply,  there  is  no  hunger.     In  fever, 
the    body    wastes    away    and    wants    nourishment;    but   the 
stomach  cannot  digest,  and  consequently  asks  for  no  food. 
When  nutriment  is  wanted,  the  body  speaks  to  the  stomach, 
and  the  stomach,  if  it  have  power  of  digestion,  speaks  to  the 
nervous  system.     This  is  hunger.     This  sensation  is  felt  in 
the  stomach,  and  there  it  continues  until  all  the  gastric  juice 
which   will  dissolve  the  needed  quantity  of  food  is  poured 
out  and  combined  with  it,  and  then  it  ceases  for  the  time. 

43.  An  industrious  man,  who  imagines  the  time  spent  at 
table  to  be  lost,  complains  that  he  has  a  very  great  appetite, 
but  a  very  weak  and  painful  digestion.    He  says  that  he  sits 
down  to  his  dinner  voraciously  hungry,  and  eats  very  rapidly, 
without  giving  his  mouth  time  to  masticate  his  food.    He  eats 
much  more  than  his  companions,  and  yet  he  rises  from  the- 
table  hungry,  and  goes  immediately  to  his  work,  from  which 
he  is  absent  a  shorter  time  than  his  fellows,  who  eat  less  than 
he  does.     His  hunger  continues  about  twenty  minutes  or 
half  an  hour  after  he  leaves  the  table,  and  then  he  is  in  pain. 
His  food  oppresses  him  ;  it  lies  like  a  weight  in  the  stomach 
for  several  hours ;  and  he  is  scarcely  relieved  of  the  distress 
before  the  time  for  another  meal  comes  round. 

44.  The  explanation  is  this :  Mr.  D.  is  a  man  of  active 
habits,  and  his  frame  therefore  wants  nutriment.     His  stomach 
can  digest  and  is  ready  to  give  out  gastric  juice  sufficient  to 
dissolve  as  much  food  as  is  needed,  and  he  is  consequently 
hungry.     To  gratify  his  keen  appetite,  and  .to  save  time  at 
his   meals,  he   has   acquired   the  unnatural  habit  of  eating 


28  PHYSIOLOGY    AND   HEALTH. 

rapidly.  He  swallows  his  food  faster  than  the  gastric  juice 
is  prepared  to  mix  with  it.  Before  enough  of  this  fluid  is 
poured  out  for  the  first  morsel,  the  second  is  swallowed,  and 
before  this  is  moistened,  a  third  arrives;  and  thus  every 
moment  increases  this  mass  of  food  waiting  in  the  stomach 
for  its  dissolving  fluid.  As  long  as  this  juice  continues  to 
flow,  there  is  an  appetite.  But  before  it  ceases,  he  has  eaten 
so  much  that  his  tardy  reflections  tell  him  that  he  has  eaten 
enough,  and  more  than  enough.  Obedient  to  his  reflections 
rather  than  to  his  sensations,  he  rises  from  his  table  before  he 
has  satisfied  his  appetite,  which  continues  for  several  minutes 
longer,  until  the  gastric  juice  ceases  flowing  and  mixing 
with  the  food.  When  this  happens,  there  is  yet  in  the 
stomach  some  food  unmixed  with  the  fluid,  and  this  is  so 
much  more  than  can  be  dissolved.  The  stomach  struggles 
painfully  for  several  hours  to  digest  or  get  rid  of  this  excess, 
and  hence  comes  the  oppression  that  hangs  heavily  upon  him 
through  the  interval  between  his  meals. 

45.  The  work  of  digestion  commences  immediately  after 
we  begin  to  eat;  as  soon  as  we  swallow  one  morsel,  some 
gastric  juice  is  given  out  and  combines  with  it.  The  second 
morsel  excites  the  flow  of  more  of  this  fluid,  and  enough  for 
its  own  solution.  In  the  same  manner,  each  successive 
morsel  provokes  the  secretion  of  as  much  of  this  fluid  as  it 
needs,  until  all  shall  be  given  out  that  can  be  given  at 
that  time.  If,  therefore,  we  eat  slowly  and  naturally,  by  the 
time  that  we  shall  have  finished  eating,  all  the  food  will  be 
moistened.  In  a  few  minutes  more,  all  the  gastric  juice  tha+ 
can  be  prepared  on  that  occasion  is  thrown  into  the  stomach ; 
and  this  is  sufficient,  in  health,  to  dissolve  as  much  food  aa 
the  nutrition  of  the  system  then  needs,  and  no  more. 


DIGESTION  A^n  FOOD.  29 


CHAPTER  V. 

Motions  of  the  Stomach.  —  Digested  Food  homogeneous.  —  Heat  of 
Stomach  during  Digestion.  —  Cold  interrupts  Digestion.  —  Py loric 
Valve. 

46.  THIS  mixture  of  the  fluid  with  the  food  in  the  stomach 
is  aided   by  the  action   of  its  muscular  coat,  and   of  the 
muscles  of  respiration.     The  muscular  coat  habitually  re- 
duces the  size  of  the  sack  down  to  its  contents.     When 
more  food  or  drink  is  received,  it  relaxes,  and  allows  the  sack 
to  expand  and  give  the  new  matter  room.     But  this  coat  is 
uneasy.     It  not   only  relaxes,  but   it   again   contracts,   and 
presses  upon  the  food ;   and  then  again  it  loosens.     This  is 
repeated  gently   and  continually;    and    by  this  means   the 
food  is  kept  in  slight  motion,  as  long  as  the  process  of  diges- 
tion is  going  on.     These   movements   are    assisted   by  the 
muscles  of  respiration.     The  stomach  lies  in  the  upper  part 
of  the  abdomen,  (Fig.  V.  /,)  and  just  below  the  chest,  where 
the  lungs  are  situated. 

47.  Immediately  above,  and  in  contact  with  the  stom- 
ach, the  diaphragm  (Fig.  V.  d)  stretches  across  the  body 
from  side  to  side,  and  from  the  back-bone  to  the  breast- 
bone.    This  great  muscle  is  the  partition  wall  between  the 
chest    and    the  abdomen,  and  moves  with   every  breath. 
Every  time  we   draw  our  breath,   this  presses  downwards 
upon  the  stomach,  enlarges  the  cavity  of  the  chest,  and  gives 
room  for  the  air  to  flow  into  the  Jungs.     Then,  when  \ve 
exhale,  the  abdominal  muscles — those  which  principally  con- 
stitute the  front  wall  of  the  abdomen  —  contract,  press  upon 
the  stomach,  and  throw  it  upon  the  diaphragm,  and  force  the 
air  outward.     Thus  the  stomach  is  kept  in  incessant  motion. 
Every  inspiration  of  air  presses  it  downward  and  outward, 
and  every  expiration  presses  it  upward  and  inward.     These 
combined  movements  keep  the  food  in  such  agitation,  that  it 
becomes  thoroughly  mixed  with  the  gastric  juice,  and  the 

3* 


30  PHYSIOLOGY   AND    HEALTH. 

digestive   process  is   by    this    means   very  materially   hast- 
ened. 

48.  The  food  is  first  mixed  with  and  then  dissolved  in  the 
gastric  juice.     Then  all  the  peculiarities  of  the  articles  which 
we  have  eaten  are  lost.     No  trace  of  the  original  form  of  the 
digestible  and  digested  matter  can  be  found.     Meat,  bread, 
fruits  —  all  are  reduced  to  one  homogeneous  pulp.     Whatever 
we  may  have  eaten,  the  pulp,  so  far  as  we  can  discover,  is 
the   same.     When  we   examine   the   digested    food   in   the 
stomach  of  the  man  whose  diet  is  mostly  meat,   in  that  of 
another  whose  diet  is  exclusively  bread,  and  in  that  of  the 
child,   whose   whole   nutriment   is   milk,  the   eye   and   the 
fingers  perceive  no  difference.      This  process   is  termed 
chymificatian ;  and  the  new  pulp  is  called  chyme,  which  is 
now  ready  to  pass  from  the  stomach  to  its  second  stage  of 
digestion  in  the  duodenum. 

49.  This  process  of  digestion  requires  the  natural  heat  of 
the  animal  body.     Dr.   Beaumont  passed   the   thermometer 
frequently  into  St.  Martin's  stomach,  and  found  that  its  tem- 
perature was  100°,  which  is  two  degrees  higher  than  the 
natural   temperature  of  the   body.     He  also  found  that  cold 
retarded  the  process  of  digestion.     He  threw  into  the  stom- 
ach a  single  gill  of  water  at  the  temperature  of  50°,  which 
reduced   the  temperature  of  the  whole  contents  of  the  stom- 
ach  30°,    that  is,  down  to  70°.     Digestion   was   then    sus- 
penfded,    until   the  temperature   was  elevated  to  its  natural 
standard. 

50.  Dr.   Beaumont  took  a  quantity  of  the  gastric  juice 
from  St.  Martin,  and  divided  it  into  two  portions.     He  put 
some  pieces  of  meat  into  one  portion  of  this,  cooled  down  to 
34°,   and  some  into  another  portion,  warmed  to   100°,  the 
natural  temperature  of  the  stomach  during  digestion.     These 
were  kept  at  these  temperatures  for   many  hours.     At  the 
same  time  St.  Martin  swallowed  meat  of  the  same  kind.     In 
one  hour  the  meat   in  the  stomach  was  partially  chy mined  ; 
that  in  the  warm  gastric  juice  out  of  the  stomach  was  nearly 
in  the  same  condition,  while  that  in  the  cold  gastric  juice 


DIGESTION    AND    FOOD.  31 

was  much  less  advanced.  When  the  meat  was  entirely  di- 
gested in  the  warm  fluid,  it  was  very  little  changed  in  the 
cold  fluid.  At  the  end  of  twenty-four  hours  the  last  was  no 
more  digested.  But  then  he  warmed  this  fluid  to  100°,  and 
kept  it  at  that  temperature,  and  digestion  commenced  and 
advanced  regularly,  as  in  the  other  parcels. 

51.  In  his  other  experiments,  Dr.  Beaumont  found  that 
cold    gastric    juice    acted   not  at  all,    or   very    imperfectly. 
Hence  he  concluded  that  heat  to  a  certain  degree  is  neces- 
sary, to  give  it  the  power  of  dissolving  food.     Dr.  Carpenter 
thence  infers  that  the  practice  of  eating  ice  after  dinner,  or 
even  drinking  cold  fluids  or   ice-water  during  dinner,  or  at 
any  time  of  eating,  is  very  prejudicial   to  digestion.     If  this 
be  true,  then  all  drinks  which  are  colder  than  the  stomach 
must  interfere  with  the  action  of  the  gastric  juice  to  an  ex- 
tent in  proportion  to  their  coldness.     For,  if  a  temperature  of 
100°  is  necessary  for  digestion,  then  any  thing,  whether  food 
or  drink,  that  cools  the  gastric  juice  below  this  degree,  must 
suspend  the  digestive  process  until  the  heat  of  the  body,  or 
living  power  of  the  stomach,  shall  warm  the  fluid  up  to  the 
necessary  temperature. 

52.  The  stomach  (Fig.  IV.)  is  large,  and  has  its  principal 
cavity  at  the  left  end,  where  the  food  is  received  through  the 
oesophagus  from  the  mouth.     It  grows  smaller  towards  the 
opposite  end,  and  finally  opens,  by  a  small  aperture  at  its  right 
extremity,  into    the  intestinal  canal.     At  this  point  of  junc- 
tion, it  is  surrounded  by  a  strong  circular  band  of  muscular 
fibres,  which,  by  contraction,  can  completely  close  the  open- 
ing, as  a  string  closes  the  mouth  of  a  bag,  and  prevent  the 
passage  of  any  thing  through.     This  is  the  pyloric  valve, 
(Fig.  IV.  b,)  which  acts  as  a  faithful  sentinel,   and  retains 
the  contents  of  the  stomach  during  the  process  of  digestion. 
While  the  food  is  undergoing  the  operation  of  churning  and 
mingling  with  the  gastric  juice,  it  binds  itself  closely  around 
the   passage-way.     The   motions   of  the   stomach,    and  the 
pressure  of  the  respiratory   muscles,    would   very   naturally 
force  the  food  out  of  this  sack,  if  it  were  not  thus  effectually 
secured. 


32  PHYSIOLOGY    AND    HEALTH. 

53.  This  ever-watchful  door-keeper  has  a  special  duty  to 
perform.     Its  business  is  to  retain  the  food  in  the  stomach 
until  it  be  digested,  and  then  to  let  it  pass  onward.     For  this 
purpose,  it  seems  to  be  endowed  with  a  kind  of  intelligence, 
by  which  it  discriminates  between  the   crude   and  the  dis- 
solved matters  that  present  themselves  to  it,  and  with  a  sort 
of  discretionary  power,  by  which  it  opens  and  lets  the  finish- 
ed  chyme  pass  out,  but  closes  and  prevents  the  passage  of 
that  which  is  not  so  reduced  to  a  pulp.     While  the  stomach 
is  empty,  it  may  be  relaxed,  and  the  doorway  left  open ;  but 
as  soon  as  any  food  is  swallowed,  it  shuts  the  door,  and  holds 
it  tight  until  this  food   be  digested.     As  fast  as  any  portion 
oi  the  food  is  turned  into  chyme,  it  is  carried  by  the  motions 
of  the  stomach  to  the  right  end ;   then  the  valve  relaxes,  the 
door  opens,  and  the  digested  food  passes  out.     But,  with  a 
quick  perception  of  the  differences  of  condition  of  the  food, 
it  closes  the  moment  the  digested  portion  has  gone  out,  and 
the  undigested  portions  offer  themselves. 

54.  We,  sometimes  eat  food  of  a  kind  which  the  stomach 
cannot  digest.     We  sometimes  eat  more  at  a  meal  than  the 
gastric  juice  can  dissolve.     In  these  cases,  the  stomach  di- 
gests what  it  can,  and  makes  great  effort  to  digest  the  rest. 
When  it  becomes  wearied  with  its  unsuccessful  efforts,  it  en- 
deavors to  relieve  itself  of  the  indigestible  portion  by  thrust- 
ing it  through  the  aperture  at  the  right  end  into  the  intesti- 
nal canal.     But  as  this  crude  matter   is  neither  digested  nor 
prepared  for  the  action  of  the  next  organ,  the  valve  refuses 
to  open  and  let  it  go  through.     Again  this  is  sent  back,  and 
again  the  stomach  makes  its  fruitless  attempts  to  digest  it  ; 
and  thus  failing  a  third  and  a  fourth  time,   presents  it  to  this 
doorway  for  passage.     This  is  refused  over  and  over ;  the 
valve  closes  with  a  greater  and    even   more   painful  force ; 
until,  at  last,  fatigued  with  the  resistance,  it  yields  to  the  im- 
portunity  of  the  stomach,   and  permits  the  undigested  and 
indigestible   matter  to  go  through.     While   this  struggle  is 
going  on,  we  feel  a  distressing  oppression  about    the  ri^ht 
side,  just  below  the  short  ribs.     This  usually  happens  within 


DIGESTION    AND     FOOD. 

two  or  three  hours  after  eating,  and  is  caused  by  the  ineffect- 
ual effort  of  the  stomach  to  convert  the  indigestible  food  into 
pulpy  chyme,  and  the  resistance  of  the  valve  to  its  passage 
outward. 

55.  But  after  a  painful  struggle  of  the  stomach  to  get  rid 
of  that  which  it  cannot  master,  and  of  the  valve  to  hold  back 
that  which  ought  not  to  pass,  the  food  is  at  length  forced  into 
the  intestinal  canal.  There  it  is  a  strange  matter;  it  is 
no  more  suited  for  this  organ  than  it  was  for  the  stomach. 
These  organs  were  made  to  receive,  the  one  masticated  and 
digestible  food,  and  the  other  the  chyme,  or  the  food  digested 
and  reduced  to  a  fine  pulp.  All  other  matters  are  foreign  to 
them,  and  create  disturbance  and  cause  pain.  The  natu- 
ral and  healthy  work  of  the  stomach  is  preparatory  to  the 
work  of  the  intestinal  canal;  and,  unless  j,he  first  organ  has 
done  its  proper  work  upon  the  food  before  it  enters  the  sec- 
ond, the  last  can  do  little,  and  generally  it  can  do  nothing 
with  it.  It  has  no  more  power  over  food  that  is  not  digested, 
than  the  other  had  over  food  that  could  not  be  digested.  As 
long  as  it  remains,  then,  in  the  body,  it  irritates  the  sack 
which  contains  it,  and  gives  distress  to  the  whole  system. 


CHAPTER  VI. 

Time  required  for  Digestion  in  the  Stomach. 

56.  DIGESTION  commences  in  the  stomach  as  soon  as  the 
food  is  swallowed,  and  continues  from  one  to  five  hours  — 
varying  according  to  the  kind  of  food,  and  the  health  of  the 
person.  Dr.  Beaumont  found  that  the  various  articles  of  diet 
differed  very  much  as  to  the  time  required  for  their  solution 
in  the  stomach.  Pigs'  feet  and  tripe  soused  were  changed 
to  chyme  in  one  hour,  while  roasted  fresh  pork  was  not  dis- 
solved in  less  than  five  hours  and  a  quarter.  Other  articles 
required  various  periods,  ranging  between  these  extremes. 
The  average  and  usual  time  required  for  the  complete  diges- 


PHYSIOLOGY    AND    HEALTH. 

tion  and  transmission  of  ordinary  meals  from  the  stomach  is 
three  hours  and  a  half.  Persons  differ  very  much,  according 
to  their  health  and  their  habits.  Those  who  have  not  abused 
their  digestive  organs  —  who  have  not  overloaded  them,  nor 
tasked  them  with  indigestible  matter  —  have  much  more  active 
stomachs  than  those  who  have  misused  these  organs.  The 
active  and  the  energetic  digest  more  vigorously  than  the 
sluggish  and  the  inert.  The  following  table,  showing  the 
time  required  for  the  stomach  digestion  of  various  articles 
of  food,  is  taken  from  Dr.  Beaumont's  work,  p.  269. 

57.    Mean   Time  required  for  the  Digestion  of  various. 
Articles  of  Food  in  the  Stomach. 


Articles. 

Prepara- 
tion. 

Ti 

'£. 
H 

nc. 

7 

Articles. 

Prepara- 
tion. 

Ti 
i 

3 

no. 

I 

Apples,  sour,  hard,. 

Raw, 
Raw, 
Raw, 

Boiled, 
Broiled, 
Boiled, 
Boiled, 
Roasted, 
Roasted, 
Broiled, 
Boiled, 
Boiled, 
Fried, 

Boiled, 

Boiled, 
Boiled, 
Baked, 
Baked, 
Melted, 
Raw, 

Raw, 

Boiled, 
Baked, 
Boiled, 
Boiled, 
Fried, 
Raw, 
Fricas'd, 
Boiled. 

2 
2 
1 
3 
3 
2 
2 
3 
3 
3 
3 
3 
4 

4 

3 

3 

3 
3 

2 

2 

4 
2 
3 
4 
3 
3 
2 
?. 

50 

30 

80 
30 

36 

10 

15 

45 
45 
30 
15 
30 
30 

30 
30 

15 
15 
30 

30 
45 

Corn,   green,   and  ) 

Boiled, 

Baked, 
Baked, 
Baked, 
Boiled, 
Roasted 
Roasted 
Boiled 
hard, 
Boiled 
soft, 
Fried, 
Roasted, 
Raw, 
Raw, 
Fried, 
Boiled, 
Roasted, 
Boiled, 
Roasted, 
Fried, 
Broiled, 
Broiled, 

Warm'd, 

Boiled, 
Raw, 

Roasted, 
Broiled, 
Boiled. 

3 

3 
3 

2 
3 

4 
4 

3 

3 

3 
2 
2 
1 
3 
4. 
4 
2 
2 
4 
2 
2 

2 

2 
2 
3 
3 
3 

4o 
15 

45 

30 
30 

30 
15 

30 
30 

30 
30 

30 

30 

15 
15 

.sweet,  do.,  . 
Aponeurosis,*    .  .  . 
Bass,  striped,  fresh, 

bread,    .... 

Dumpling,  apple,    . 
Ducks,  domesticated  , 
,  wild,  .... 

Eggs,  fresh,    .  .  .  j 

Beans   pod  

Beef,lresh,lean,  rare, 

steak, 

,  with  salt  only, 
,  with  mustard, 
,  fresh,  lean,.  . 
,  old        hard    ) 

i  -  -  -  ( 

,  .  .  .  • 

salted,   5 
Beets,  

,  .  .  .  . 

Brains     .  '. 

Flounder,  fresh,    .  . 
Fowl,  domestic,    .  . 

Bread,  wheat,  fresh, 

Cabbage  head,  .  .  . 

Goose,    
Heart 

egar,  5 

Lamb,  fresh,  .... 
Liver,  beefs,  fresh, 
Meat  hashed  with  ) 
vegetables,.  .  .  ) 
Milk              

Cake,  sponge,    .  .  . 
Carrot,  orange,     .  . 
Cartilage,*  

Catfish,  
Cheese,  old,  strong, 
Chicken,  full-grown, 
Codfish,  cured,  dry. 

Mutton,  fresh,    .  .   • 

7 

DIGESTION    AND    FOOD. 


36 


Articles. 

Prepara- 
tion. 

Time. 

Articles. 

Prepara- 
tion. 

Tii 

_E 

l\S. 

I 

i 

a 

3 

Oysters,  fresh,  .  .  . 

Raw, 

Roasted, 
Stewed, 
Boiled, 
Roasted, 
Boiled, 
Roasted, 
Boiled, 
Fried, 
Broiled, 
Raw, 
Stewed, 
Broiled, 
Boiled, 
Roasted, 
Baked, 
Boiled, 
Boiled, 
Boiled, 
Broiled, 
Boiled, 
Boiled, 

2 
3 
3 
2 
2 
1 
5 
4 
4 
3 
3 
3 
3 
3 
2' 
2 
1 
1 
4 
3 
1 
3 

55 
15 
30 
30 
30 

15 
30 
15 
15 

15 

30 
30 
30 

45 

20 
30 

Soup,  beef,  vege-  ) 
tables,  and  bread,  ^ 
,  chicken,  .  .  . 
,  marrow-boues, 
,  mutton,    .  .  . 
—  ,  oyster,  .... 
Spinal  marrow,  an-  ) 

Boiled, 

Boiled, 
Boiled, 
Boiled, 
Boiled, 

Boiled, 

Boiled, 
Boiled, 
Boiled, 
Boiled, 
Boiled, 
Boiled, 
Fried, 

Roasted, 

Boiled, 
Roasted, 
Boiled, 
Broiled, 
Fried, 
Broiled, 

4 

3 
4 
3 
3 

2 

5 
t 

2 

\ 

2 

2 
2 
3 
4 
4 
1 

15 

30 

30 

40 

30 
30 

30 

90 

30 

30 

25 
18 
30 

30 
35 

j  .  .  . 

Pig,  sucking,  .... 
Pigs'  feet,  soused,  . 
Pork,  fat  and  lean,  . 
,  recently  salt'd, 

Suet,  beef,  fresh,.  . 
,  mutton,  .... 

> 

> 

TVnrlnn  * 

steak 

Tripe,  soused,  .  .  . 
Trout,  salmon,  fresh, 

Potatoes,  Irish,  .  .  . 

7      '     •     • 

Turkey,    domesti-  ) 
cated,  ) 

Rice    . 

Sagfo 

Salmon,  salted,    .  . 
Sausage,  fresh,  .  .  . 
Soup,  barley,  .... 
•  ,  bean,  

,  wild,     *    . 
TurnipB,  flat,  .... 
Veal,  fresh,    .  .  . 

Venison  steak,  .  .  . 

*  Cartilage  is  usually  called  gristle.    Aponeurosis  and  tendon  are  very  strong  and 
tough  parts  of  the  flesh,  somewhat  similar  to  cartilage. 

58.  These  are  the  results  of  many  observations  upon 
St.  Martin.  The  time  stated  in  regard  to  each  article  is  the 
average  time  required  to  digest  it.  From  these  experiments 
we  see  that  there  is  a  very  great  difference  in  the  time 
required  for  the  stomach  digestion  of  the  various  articles  of 
food.  Rice  and  souse  are  digested  in  one  hour;  salmon 
trout  and  sweet  apples,  in  one  hour  and  a  half;  beef's  liver, 
codfish,  and  tapioca,  in  two  hours  ;  fresh  beef  and  mutton,  in 
three  hours ;  veal  broiled,  and  ducks,  in  four  hours.  Fresh 
pork,  roasted,  required  five  hours  and  a  quarter  for  digestion. 
St.  Martin's  power  of  digestion  may  not  exactly  correspond 
with  that  of  all  other  men.  Some  may  require  a  longer, 
some  a  shorter  time  to  digest  these  articles  of  food.  Still  he 
may  be  fairly  considered  as  a  representative  of  the  average 
of  mankind;  and  probably  we,  if  in  good  health,  shall  digest 
these  several  articles  in  about  the  same  time  that  he  did. 


36  PHYSIOLOGY    AND    HEALTH. 


CHAPTER  VII. 

Fluids  drunk  with  Food  impede  Digestion.  —  Stomach  acts  more 
easily  on  a  large  than  on  a  minute  Quantity  of  Food.  — Meat  bet- 
ter digested  if  mixed  with  Vegetables.  —  Gastric  Juice  mixes 
easily  with  light,  but  not  with  heavy  Bread.  —  Light  Bread  soaks 
readily  in  Water,  but  heavy  Bread  does  not. 

59.  THE  first  work  of  the  stomach   in  digestion  is  to  get 
rid  of  all  the  fluid  which  has  been  swallowed  with  the  food. 
In  fifty  minutes  after  Martin  had  dined  on  vegetables,  soup, 
beef,  and  bread,  Dr.  Beaumont  found  that  the  fluid  portion 
had  been  absorbed  and  carried  away  from  the  stomach,  and 
the  remainder  was  of  a  thicker  consistence  than  usual,  after 
a  more  solid  food  had  been  taken.     This  is  necessary,  in  or- 
der that  the  gastric  juice  shall  not  be  diluted  and  weakened, 
and  its  power  of  dissolving  the  food  diminished. 

60.  Drink  taken  with  food,  then,  must  either  reduce  the 
power  of  the  gastric  juice,  or  postpone  the  work  of  digestion 
until  the  stomach  shall   have  relieved   itself  of  this  needless 
matter,    and    in  either  case,   suspend  the  digestive  process. 
It  is  a  common  notion  that  those  who  have  weak  stomachs 
should  take  weak  broths,  soups,  teas,  &,c.,  which   seem  to 
require  less  effort  of  digestion.     But  this  is  not   always  good 
advice.     These  liquids  may    require    more    effort,  and  are, 
therefore,  inappropriate  food  for  many  of  the  feeble. 

61.  The  natural  secretions  of  the  mouth  afford  sufficient 
fluid  to  aid  in  the  grinding  and  softening  the  food,  and  to 
prepare  it  for  swallowing ;  and  the  gastric  juice  in  the  stom- 
ach is  sufficient  for  its  solution  there.     Upon  this  principle, 
tea,  coffee,  or  water  with  our  meals  cannot  be  of  advantage. 
Dr.  Warren   says,   "  The  quantity  of  drink  required  for 
health  and  comfort  is  very  small.     In  cold  weather,  a  pint 
of  liquid  in  twenty-four  hours  is  sufficient;  in  the  hot  seasons, 
this  quantity  may  be  increased ;  but  this  increase  is  rarely 
ne^essury  when  a  reasonable  amount  of  fruit  can  be  ob- 


DIGESTION    AND    FOOD.  37 

ained."  *  Dr.  Dalton  thinks  "  a  man  in  full  health,  taking 
free  exercise  in  the  open  air,  requires  rather  more  than 
three  pints  of  liquid  daily."  f 

62.  The  stomach  acts  more  easily  upon  a  large  than  on  a 
very  small  quantity  of  food.     As  the  hands  find  it  easier  to 
grasp  and  hold  a  cane  than  a  quill  or  a  wire,  and  the  arms  can 
more  easily  clasp    an  armful  of  wood  than   a  single   stick, 
so  the  muscular  coat  of  the  stomach  finds  less  difficulty  in 
grasping  and  pressing  upon  a  full  meal  than   a  little  morsel. 
The  quantity  of  nutriment  in  food  is  not  always  in  propor- 
tion to  its  bulk ;  some  kinds  contain  very  much,  and  others 
very  little,  in  the  same  space  or  weight.     A  pound  of  beef  is 
more  nutritious  than  a  pound  of  bread,  and  a  pound  of  bread 
contains  more  nutriment  than  a  pound  of  roots. 

63.  Meats  are  very  concentrated ;    that  js,  they  contain 
great  quantities  of  nutriment  in  small  bulk  ;  and  if  we  were 
to  live  upon  these  alone,  we  should  eat  a  small  quantity  — 
smaller  than    the  stomach  could  manage  with  the  greatest 
ease  to  itself.     This  difficulty  is  obviated   by  mixing  meat 
with  bread  and  vegetables.     Some  of  the  rude  tribes  in  the 
extreme  northern  regions  live  upon  the  coarsest   and  most 
concentrated  meats.     But  they  find  it  better  to  mix  this  with 
bread,  potatoes,  or  other  roots,   with  bran,  or  even  sawdust, 
for  the  purpose  of  facilitating  the  action  of  the  stomach. 

64.  In  order  that  the  food  should  be  mixed  the  most  freely 
with  the  gastric  juice  in  the  stomach,  it  should  be  not  only 
well  divided  in  the   mouth,  but  it  should  be  of  such  a  nature 
that    the    gastric    juice  can  get  access  to  all  the  minute  par- 
ticles, and  separate  them  from  each  other.     With  light  bread, 
that  is  thoroughly  baked,  and  somewhat  dried,  this  is  easily 
accomplished.     But  heavy  bread  is  cohesive,  and  the  parti- 
cles cling  together  and  form  a  solid  mass,  so  compact  that  it 
would  be  very  difficult  for  any  fluid  to  penetrate  it. 

65.  The  difference  is  easily  shown,  and  is*  probably  famil- 
iar to  all ;  if  not,  the  experiment  can  be  tried  in  one  moment, 
by  throwing  a  piece  of  light,  porous  bread,  that  has    been 

*  On  Preservation  of  Health,  p.  G2.  f  Physiology,  p.  113. 

4 


38  PHYSIOLOGY    AND    HEALTH. 

baked  twenty-four  hours,  and  is  somewhat  dried,  into  water. 
Immediately  the  water  penetrates  into  all  the  cells,  and  fills 
all  the  pores ;  the  bread  absorbs  more  and  more,  and  swells ; 
and  soon  the  mass  is  much  enlarged,  and  is  completely  filled 
with  water.  In  fact,  it  is  itself  mere  pulp.  If  we  divide  it, 
we  shall  find  that  water  has  come  in  contact  with  every  par- 
ticle ;  every  one,  however  minute,  is  wet. 

66.  Again,  throw  a  piece  of  heavy,  compact  bread,  that 
has  no  cells  in  it,  into  water,  and  let  it  remain  as  long  as  the 
other,  and  then  examine  it,  and  it  will  be  found  that  it  is  as 
heavy  as  it  was  before ;  the  water  has  not  penetrated  it  —  it 
has  absorbed  none ;    it  is  not  enlarged,  and  the  inner  parti- 
cles are  not  reached  by  the  fluid ;  they  are  as  dry  as  they 
were  before  the  piece  was  thrown  into  water.     The  same 
effect  takes  place  in  the  action  of  the, gastric  juice  in  the 
stomach.   .It  finds  it  easy  to  penetrate  among  and  wet  the 
particles  of  the  light,   and   hard  to  enter  the   heavy  bread. 
This  last  then  remains  for  a  long  time  a  solid,  compact  mass, 
or  a  mass  of  compact  portions,  which  cannot  be  dissolved ;  or, 
if  it  be  dissolved,  it  is  not  without  much  difficulty  and  pain, 
and  after  a   long   perseverance   of  the  organ  in  its    almost 
fruitless  work. 

67.  We  can  determine  this  quality  of  bread  even  without 
the  trouble  of    throwing    it    into    water.      New    bread   is 
almost  always  cohesive,  and  its   particles   disposed  to  cling 
together.     If  we  take  a  piece  of  this,  or  of  heavy  bread,  and 
roll  it  between  the  fingers,  it  forms  into  a  compact  ball  or 
roll,  so  close  that  it  is  plain  that  it  will  not  readily  admit  wa- 
ter to  soak  it.     But  if  we  try  the  same  with  old  and  light 
bread,  it  separates  and  falls  into  crumbs.     It  is  impossible 
to  make  it  into  a  ball.     This  would  be  easily  soaked   in 
water,  and  easily  digested  in  the  stomach,  which  is  not  the 
case  with  the  new  or  the  heavy  bread. 


DIGESTION    AND    FOOD,  39 


CHAPTER  VIII. 

Chyme. —  Intestinal  Canal.  —  Mucous  Membrane. — Lacteals. — 
Chyme  in  the  Duodenum.  —  Chyle :  differs  with  difference  of 
Food.  —  Carried  to  Blood-Vessels.  —  Three  Stages  of  Digestion. 

63.  "When  the  stomach  has  finished  its  work,  the  food  is 
converted  into  chyme.  To  the  naked  eye,  it  is  the  same  in 
appearance  throughout.  All  distinctions  of  the  various 
kinds  of  aliment  seem  to  be  lost.  No  traces  of  the  meats, 
bread,  or  vegetables  are  visible ;  all  are  reduced  to  an  ap- 
parently homogeneous  pulp.  These  were  the  former  no- 
tions of  science.  But  modern  microscopic  investigations 
and  chemical  analyses  show  that  this  is  not  homogeneous ;  of 
this  a  part  only  is  digested,  or  converted  to  chyme ;  the  rest, 
though  finely  divided  and  mixed  with  the  fluids  of  the  stom- 
ach, is  yet  to  be  submitted  to  a  farther  process  of  digestion 
in  the  small  intestines.  When  the  stomach  has  finished  its 
work  on  the  food,  the  pyloric  valve  opens,  the  muscular 
coal  contracts,  and,  pressing  upon  the  contents,  forces  this 
pulp  through  this  passage  into  the  duodenum,  (Fig.  IV.  c,  c,) 
which  is  the  next  link  in  the  alimentary  canal. 

69.  The  intestinal  canal  is  composed  of  three  coats, 
which  are  similarly  arranged  and  serve  similar  purposes  to 
those  of  the  stomach.  The  outer  of  these  coats  is  strong 
and  thick,  and  gives  support  to  the  whole  canal ;  by  this  coat 
the  organ  is  attached  to  the  back-bone  and  held  in  its  place. 
The  middle  coat  is  like  the  lean  meat  of  tripe ;  it  is  com- 
posed of  two  sets  or  layers  of  fibres,  one  of  which  winds 
around  the  tube  —  the  other  runs  lengthwise  from  end  to 
end.  The  circular  band  regulates  the  size  of  the  tube,  by 
keeping  it  always  pressed  down  upon  its  contents.  When  food 
is  within  this  organ,  these  fibres  contract,  one  after  another, 
successively,  and,  pressing  upon  the  matters  contained  within, 
force  them  onward.  The  longitudinal  fibres  shorten  the 


40  PHYSIOLOGY    AND    HEALTH. 

canal  or  its  parts,  and  by  this  means  they  aid  in  carrying 
the  food  forward. 

70.  The  inner  lining,  called  the  mucous  membrane,  se- 
cretes the  slimy  mucus  with  which  the  whole  inner  surface 
of  the  canal  is  moistened  and  protected  from  any  irritating 
quality  of  the  contents.     This  membrane  is  loose  and  flab- 
by, and,  when  the  canal  is  empty  and  contracted,  it  is  drawn 
into  wrinkles  or  folds,  and  seems  to  be  too  large  for  the 
sack.     But  when  the  canal  is  distended  with  food,  or  any 
other  matter,  it  is  drawn  out,  and  lies  more  smoothly  over 
the  inner  face  of  the  sack.    Besides  these  folds,  which  are 
made  in  the  mucous  membrane  by  the  contraction  of  the 
canal,  there  are  other  folds,  which  run  around  the  inner 
surface  of  the  tube  crosswise  its  length.    These  are  perma- 
nent, whether  the  tube  be  contracted  or  distended.     This 
membrane  or  lining  of  the  intestine  is  furnished  with  a  set 
of  glands,  which  prepare  and  throw  into  the  canal  a  pecul- 
iar fluid  called  the  intestinal  juice.     This  is  another  coop- 
erator  in  the  work  of  digesting  the  food  and  fitting  it  for 
the  blood.     It  meets  and  combines  with  the  chyme  in  this 
part  of  the  alimentary  canal,  or  the  duodenum,  and  there 
it  digests  or  changes  some  of  the  elements  of  the  food  that 
had  not  been  so  changed  by  the  fluids  in  the  stomach. 

71.  The  pancreas  is  a  large  gland  lying  behind  the  stom- 
ach, and  performs  an  important  part  in  the  work  of  digestion. 
It  prepares  another  fluid,  called  the  pancreatic  juice,  and 
sends  it  through  a  tube  into  the  upper  part  of  the  duodenum. 
This  juice  enters  into  combination  with  still  other  elements 
of  the  food,  especially  the  oily  matters  or  fats,  which  had 
not  been  affected  by  the  gastric  or  intestinal  juices,  and 
prepares  these  for  the  use  of  the  blood. 

72.  Thus  each  of  these  three  different  digestive  fluids  or 
juices  —  prepared  in  the  stomach,  the  duodenum,  and  the 
pancreas  —  performs  its  own  and  peculiar  part  in  the  work 
of  digestion.     They  convert  the  nutritive  elements  of  the 
food  into  a  condition  fit  to  enter  and  become  a  part  of  the 
blood.    These  elements  constitute  a  milky  fluid  called  chyle, 
which  is  yet  in  the  alimentary  can  il ;   but  it  is  destined  to 


DIGESTION    AND    FOOD.  41 

nourish  the  whole  body,  and  must  first  pass  into  and  through 
the  blocd-vessels. 

73.  The  mucous  membrane,  or  inner  lining  of  the  intes- 
tinal canal,  is  soft,  like  velvet,  and  filled  with  myriads  of 
pores,  which  perform  an  important  part  of  the  work  of  di- 
gestion.   These  numberless  little  pores,  or  tubes,  have  their 
open  mouths  upon  the  inner  surface  of  the  intestinal  canal. 
They  run  from  the  inner  channel  outward  through  the  walls 
of  this  canal.     Their  mouths  are  so  small  as  to  be  invisible, 
except  by  aid  of  a  powerful  microscope ;  and  yet  they  are  so 
numerous  as  to  cover  over  all  the  inner  surface  of  this  organ. 
Their  duty  is  to  absorb,  or  suck  up,  some  of  the  nutritious 
portion  of  the  digested  food,  which,  when  it  is  in  these  little 
tubes,  has  the  appearance  of  milk.     These  are,  therefore, 
called  the  lacteal  absorbents.     These  tubes,  -when  they  first 
start  from  the  inside  of  the  canal,  are  almost  inconceivably 
small,  but  they  unite  together,  two  and  two,  and  more,  and 
thus  become  fewer  and  larger.    The  larger  tubes  again  unite, 
and  form  other  and  still  larger  ones,  until  they  all  are  joined 
in  one  large  tube,  called  the  thoracic  lacteal  duct.    This  goes 
along  the  inner  side  of  the  back-bone,  from  the  abdomen  to 
the  upper  part  of  the  chest,  and  opens  into  the  great  vein,  at 
the  right  side  of  the  heart.    These  mouths  and  tubes,  small 
and  large,  and  this  duct,  constitute  what  is  called  the  lacteal 
system.     Its  object  is  to  carry  the  nutritious  portion  of  the 
chyme  from  the  digestive  organs  to  the  blood-vessels. 

74.  Beside  these  lacteal  absorbents  there  is  another  set 
of  vessels  that  assist  in  doing  the  same  work  in  the  lining 
membrane  of  the  intestinal  canal.     These  are  myriads  of 
veins,    as    minute    as   the   lacteals.      They    absorb    ether 
portions  of  the  digested  food,  and  carry  it  through  their 
minute  tubes  into  larger  channels,  and  these  pour  their 
contents  finally  into  the  great  vein  near  the  heart. 

75.  In  the  duodenum,  or  the  upper  portion  of  the  intes- 
tinal canal,  the  digested  food  is  divided  into  two  kinds 
— •  that  which  is  to  enter  the  blood-vessels,  and  the  waste. 

4* 


42  PHYSIOLOGY    AND    HEALTH. 

The  former  alone  is  needed  for,  or  can  give  nourishment 
and  strength  to,  the  body.  The  latter  is  not  only  useless, 
but  a  burden  on  the  whole  system,  and  must  be  regularly 
excluded.  Otherwise  all  the  powers  are  oppressed,  and 
health  suffers. 

76.  The  proportion  of  this  chyle,  which  the  absorbents  are 
able  to  extract  from  the  chyme,  varies  with  the  food ;  for  one 
kind  contains  a  much  greater  ratio  of  nutriment  than  another, 
as  will  be  hereafter  shown.     It  depends  also  upon  the  com- 
pleteness  of  digestion    in    the  stomach ;  and   this,  in  great 
measure,  upon  the  perfectness  of  the  mastication  and  mixture 
with    saliva   in  the    mouth.      Of  course,    then,  the  remote 
result  of  imperfect    mastication  and  hasty  eating  mast   be, 
first,  imperfect  digestion ;    second,  less  chyle ;    and,  conse- 
quently, less  nutriment  for  the  body. 

77.  Thus  the  work  of  digestion  is  shown  to  be  performed 
by  means  of  the  mouth,  the    stomach,   and  the  alimentary 
canal.     The  whole   process   is  divided   into  three  stages  — 
mastication  and  insalivation  in  the  mouth;  the  digestion,  or 
conversion  into  chyme  in  the  stomach ;  the  separation  of  the 
nutritious   and  innutritio'us   parts  in  the  duodenum.     It  is 
necessary  that  each  part  should  be  well  done,  and  in  due 
order ;  else  all  that  follow  will  be  badly  done.* 

*  Dr.  Dalton  says,  "  We  find,  then,  that  the  digestion  of  the  food  is  not 
a  simple  operation,  but  is  made  up  of  several  different  processes,  •which 
commence  successively  in  different  portions  of  the  alimentary  canal.  In 
the  first  place,  the  food  is  subjected  in  the  mouth  to  the  physical  opera- 
tions of  mastication  and  insalivation.  Reduced  to  a  soft  pulp,  and  mixed 
abundantly  with  the  saliva,  it  passes,  secondly,  into  the  stomach.  Here 
it  excites  the  secretion  of  the  gastric  juice,  by  the  influence  of  which  its 
chemical  transformation  and  solution  are  commenced.  If  the  meal  con- 
sists wholly  or  partially  of  muscular  flesh,  the  first  effect  of  the  gastric 
juice  is  to  dissolve  the  intervening  cellular  substance  by  which  the 
tissue  is  disintegrated  and  liquefied.  In  the  small  intestine  the  pancre- 
atic and  intestinal  juices  convert  the  starchy  ingredients  of  the  food  into 
sugar,  and  break  up  the  fatty  matter  into  a  fine  emulsion,  by  which  they 
are  converted  into  chyle. 

"Although  the  separate  actions  of  these  digestive  fluids,  however, 


DIGESTION 


CHAPTER  IX. 

Digestive  Process  wonderful.  —  We  are  responsible  for  the  Selection 
and  the  Preparation  of  our  Food.  —  Healthy  Digestion  comforta- 
ble.—  Hunger  not  owing  to  Emptiness  of  Stomach.  —  Brain  and 
Nerves  must  be  sound,  to  perceive  Hunger. 

78.  THIS    digestive  process,    which   effects    so   great    a 
change,  is    wonderful,   as  well    as    interesting.     The   food, 
which  was  of  every  sort,  —  meat,  fish,  bread,  vegetables,  and 
fruit,  —  mere  lifeless  matter  upon  our  tables,  —  is  now  changed 
into  chyle,  that  is  homogeneous,  and  almost  endowed  with 
life.     It  was  at  first  the  food  for  the  stomach ;  it  is  now  nu- 
triment for  the  blood.     This  change  is  a  vital  one ;  at  least 
it  is  effected  by  the  fluids  which  are  within  the  living  body, 
and  which  are  the  product  of  vital  or  living  organs.     By 
what  unseen  agency  these  fluids  obtain  this  power,  is  known 
only  to  the   all-wise  Creator.     It  is  not  revealed  to  us,  nor 
need   it   be.     Enough  is   revealed  for    our   government,   to 
show  us  our  duty  in  regard  to  food  and  digestion. 

79.  In  this  work,  man  has  much  to  do.     He  is  to  provide 
food  of  suitable  kinds,   and  must  prepare  it   in    a   suitable 
manner.     He  is  to  determine  the  quality,  and  measure  the 
quantity,  which  he  shall  eat.     The  times  of  his  eating,  and 
the  intervals  between  his  meals,  are  left  to  his    discretion. 
The  work  of  the  mouth  is  under  his  control.     But  all  the 

commence  at  different  points  of  the  alimentary  canal,  they  afterwards  go 
on  simultaneously  in  the  small  intestine ;  and  the  changes  which  take 
place  here,  and  which  constitute  the  process  of  intestinal  digestion,  form 
at  the  same  time  one  of  the  most  complicated,  and  one  of  the  most 
important,  parts  of  the  whole  digestive  function."  —  Human  Physiol- 
ogy, p.  15G. 


44  PHYSIOLOGY    AND   HEALTH. 

operations  of  the  digestive  organs,  beyond  the  mouth,  are  not 
submitted  to  his  direction,  nor  even  to  his  observation. 

80.  When  we  are  in  good  health,  and  the  food  is  properly 
selected,  prepared,  and  eaten,  we  are  not  conscious  of  the 
process  of  digestion    in    the  stomach ;    but   if  the   food  be 
not  properly  selected   or  cooked,  if  we  have  not  faithfully 
prepared  the  food,  by  complete  mastication  and  mixture  with 
the  saliva  in  the  mouth,  for  the  next  stage  of  digestion  in 
the  stomach,  we  are  painfully  conscious  of  the  effort  of  the 
stomach  to  digest  that  which  is  unsuitable  for  its  wants  and 
its  powers. 

81.  Although  we  are  not  conscious  of  the   process   of 
digestion   from    any    feeling  that  we    have  in  the    stomach 
especially,    yet    there    is    always    a    pleasurable    sensation 
throughout  the  whole  frame,  which  accompanies  the  proper 
arid  healthy  performance  of  this  function;  there  is  a  feeling 
of  comfort  in  the  body,  and  satisfaction  in  the  mind,  and 
usually  a  glow  of  cheerfulness  attending  it.     One  feels  bet- 
ter, and  more  disposed  to  be  contented,  after  his  meals. 

82.  Our  part  of  this  work  is  to  select  the  food,  and  pre- 
pare it,  by  suitable  combinations  and  cookery,  for  the  mouth. 
Next,  we  are  to  masticate  and  moisten  it  in  the  mouth  for 
the  stomach.     After  this,  nature  takes  care  of  it.     We  want, 
then,  some  guide  to  direct  us  in  regard  to  the  quality  and 
quantity  of  this  food,  and  the  time  and  seasons  for  eating. 

83.  Hunger  and  appetite  are  the  first  apparent  guides,  and 
with  many,  perhaps  a  majority  of  mankind,  the  only  guides 
in  the  matter  of  eating.    Hunger  has  been  explained  (§  42) 
to  be  the  sensation  of  want  of  nutrition  in  the  general  sys- 
tem, connected  with  the  power  of  digestion  in  the  stomach, 
and  with  the  readiness  of  the  stomach  to  supply  the  gastric 
juice  for  this  purpose. 

84.  It  is  commonly  supposed  that  hunger  is  a  mere  indi- 
cation of  emptiness  of  the  stomach;  that  as  soon  as  the  last 
meal  shall  have  passed  out  of  this  organ,  more  is  wanted  ; 
and  that  as  long  as  any  food  remains  in  it,  there  is  no  appe- 
tite.    Neither  of  these  suppositions  is  correct.     The  usual 


DIGESTION    AND    FOOD.  45 

meals  are  digested  and  carried  into  the  intestinal  canal,  and 
the  stomach  is  left  without  food,  in  about  three  hours  and  a 
half,  (§56,  p.  33;)  and  if  they  were  composed  of  the  most 
digestible  articles,  this  time  would  be  much  less.  Yet  hun- 
ger does  not  usually  return  in  less  than  five  or  six  hours. 
This  leaves  the  stomach  empty  nearly  half  the  time,  without 
any  craving  desire  of  food. 

85.  So  certainly  is  the  desire  of  food  the  result  of  wants 
of  the  system,  in  connection  with  the  power  of,  and  readi- 
ness for  digestion,  that  in  some  diseased  states  of  the  system, 
where   both   these  conditions   exist,  but  no  communication 
between  the  stomach  and  the  blood-vessels,  the  appetite  is 
ravenous. 

86.  The  wants  of  the  whole  body  for  more  nutriment  are 
communicated  first  to  the  stomach,  and  thejice  to  the  brain. 
Here  is  the  real  sensation  of  appetite.     It  therefore  is  neces- 
sary, not  pnly  that  the  stomach  should  be  in  sound  condition, 
but  also  that  the  brain  be  in  a  condition  to  recognize  this 
feeling  of  want.     This  feeling  is  conveyed  through  the  nerves 
from  the  stomach  to  the  brain,  and  there  perceived  and  rec- 
ognized.    If,  then,  the  nerve  of  the  stomach  be  diseased  or 
divided,  there  can  be  no  communication  from  this  organ  to 
the  brain,  and  hence  no  sensation  conveyed,  and  no.  hunger 
felt.     Some  physiologists  have  tried  the  experiment  of  cutting 
the  nerves  which  connect  the  stomach  with  the  brain  in  dogs. 
The  consequence  was,  that  the  animals  seemed  to  have  lost 
all  sensation  of  appetite,  and  although  they  had  been  long 
deprived  of  food,  and  were  really  in  need  of  it,  they  did  not 
appear  to  feel  or  to  understand  the  want  of  it. 

87.  The  appetite,  then,  is  felt  in  the  brain ;  but  it  is  not 
perceived,  nor  are  we  conscious  of  it,  unless  we  can  give 
attention  to  it.     It  not  unfrequently  happens  that  one  is  so 
intently  engaged  in  any  pursuit,  that  he  forgets  his  hours  of 
eating  and  his  own  necessities.     Students  are  sometimes  so 
devoted  to  their  books,  that  their  meals  do  not  occur  to  them. 
Men  who  are   absorbed   in  any  care  or  anxiety  pay  less  than 
due  attention  to,  and  do  not  perceive,  their  craving  sensations. 


46  PHYSIOLOGY    AND    HEALTH. 

Sailors,  in  times  of  peril  and  shipwreck,  may  go  from  morn- 
ing till  night  without  thinking  of  dinner.  The  anxious 
mother,  watching  over  a  sick  child,  often  needs  to  be  re- 
minded by  others  of  the  time  and  necessity  of  eating. 

88.  A  merchant,  whose  business  during  the  whole  day 
is  in  the  city,  and  whose  employment  often  absorbs  his 
whole  attention,  sometimes  returns  at  night  to  his  home  in 
the  country  with  a  great  appetite ;  for  he  has  been  so  much 
occupied  that  he  has  forgotten  his  dinner.  And  when  thus 
engaged,  it  is  only  at  night,  when  business  hours  are  passed, 
and  his  occupation  has  ceased,  that  he  gives  any  heed  to  the 
wants  of  his  system,  or  discovers  that  he  is  hungry ;  and 
then,  from  his  previous  exhaustion  and  want  of  supply,  his 
hunger  returns  with  double  force. 

89  In  these  and  in  similar  cases,  one  may  not  feel  appe- 
tite sufficient  to  warn  him  of  the  hours  of  eating,  although, 
at  the  same  time,  his  system  is  in  want  of  nutriment,  and 
there  is  real  cause  of  hunger  without  the  sensation.  For 
the  body  is  suffering  from  the  waste  of  its  particles  and  from 
the  privation  of  food ;  the  stomach  is  empty,  and  it  has  sent 
the  warning  of  this  emptiness  to  the  brain;  but  if  this  organ 
gives  ho  attention  to  it,  no  sensation  is  felt,  nor  hunger  per- 
ceived. This  happens  for  the  same  reason  that,  when  we  are 
sometimes  absorbed  in  thought,  we  do  not  hear  the  church 
clock  strike,  although  very  near  us,  or  even  the  house  clock 
in  the  same  room  with  us.  In  this  case,  the  impulse  was 
given  ,to  the  air,  and  communicated  to  the  tympanum  of  the 
ear,  but  the  brain  was  directing  its  attention  elsewhere, 
and  perceived  no  sound. 


DIGESTION    AND    FOOD.  47 


CHAPTER   X. 

Appetite  affected  by  State  of  Mind.  —  No  Digestion  without  Appe- 
tite.—  Appetite  not  always  a  Sign  of  digestive  Power.  —  Appetite 
and  Taste  not  identical.  —  Great  Privation  of  Appetite. 

90.  The  appetite  is  affected  by  the  state  of  health  both  of 
the  body  and  of  the  mind.     In  fever,  in  pain,  and  in  certain 
dyspeptic  states,  the  stomach  craves  little  or  no  food.     So, 
in  mental  distress,  in  times  of  great  fear  or  sorrow,  .or  ex- 
treme anxiety,  the  appetite  fails.     Even  in  a  single  moment 
the  appetite  may  be  suspended  by  any  sudden  mental  affec- 
tion or  emotion.     If  any  one  sit  down  at  a  tattle  with  even  a 
strong  desire  of  food,  and  if,  when  about' to  eat  what  seems 
to  him  inviting,  he  should  be  told  of  ine  death  or  extreme 
danger  of  a  near  friend,  at  once  all  appetite  is  gone.* 

91.  Hunger  is  given  to  us  as  a  guide  to  our  duty  in  the 
work  of  sustenance;  and  when  properly  regarded,   it  is  a 
safe  guide.    It  indicates  the  wants  of  the  system  for  more 
nutriment.     Even  in  a  good  state  of  health,  these  wants  vary 

*  Dr.  Dalton  says,  "  The  secretion  of  the  gastric  juice  is  much  influ- 
enced by  nervous  conditions.  It  was  noticed  by  Dr.  Esaumont,  in  his 
experiments  upon  St.  Martin,  that  irritation  of  the  tenper,  and  other 
moral  causes,  would  frequently  diminish,  or  altogether  suspend,  the  sup- 
ply of  the  gastric  fluids.  Any  febrile  action  in  the  system,  or  any  un- 
usual fatigue,  was  liable  to  exert  a  similar  effect.  Eve  ry  one  is  aware 
how  readily  any  mental  disturbance,  such  as  anxiety,  ar  jer,  or  vexation, 
will  take  away  the  appetite,  and  interfere  with  digestion.  Any  nervous 
impression  of  this  kind,  occurring  at  the  commencement  of  digestion, 
seems  moreover  to  produce  some  change  which  has  a  Ir.  sting  effect  upon 
the  process ;  for  it  is  very  often  noticed  that,  when  any  r.unoyance,  hurry, 
or  anxiety  occurs  soon  after  the  food  has  been  taken,  though  it  may  last 
only  for  a  few  moments,  the  digestive  process  is  not  only  liable  to  be  sus- 
pended for  the  time,  but  to  be  permanently  disturbed  during  the  entire 
day.  In  order  that  digestion,  therefore,  may  go  on  properly  in  the  stom- 
ach, food  must  be  taken  only  when  the  appetite  demands  it;  it  should 
also  be  thoroughly  masticated  at  the  outset ;  and,  finally,  belli  mind  i.n  J 
body,  particularly  during  the  commencement  of  the  process,  should  be 
free  from  any  unusual  or  disagreeable  excitement."  —  Physiology,  p.  149. 


48  PHYSIOLOGY    AND    HEALTH. 

with  many  outward  and  inward  circumstances.  They  differ 
with  the  manner  of  life,  and  with  the  quantity  and  energy  of 
exercise.  The  laborious  and  active  have  more  hunger  than 
the  idle  and  the  slow.  Children  and  youth  who  are  growing 
in  stature,  convalescents  who  are  regaining  lost  flesh,  have 
more  imperative  appetites  than  others.  Appetite  is  more 
keen  when  the  body  is  in  full  vigor,  and  all  the  functions 
are  performed  with  the  most  energy.  When  the  blood  flows 
freely  and  the  muscles  play  smoothly,  when  the  mind  is 
buoyant  and  the  spirit  joyous,  the  appetite  boldly  indicates 
a  want  of  food  in  the  whole  system,  and  a  ready  power  of 
the  stomach  to  digest  it,  and  convert  it  into  the  nutriment 
of  the  blood. 

92.  Appetite  is  usually  the  sign  of  digestive  power.     Cer- 
tainly there  is  no  vigorous  digestion  without  it.     When  the 
digestive  organs,  nerves,  and  brain,  are  apparently  in  good 
condition,  and  we  are  attentive  to  the  warnings  of  the  stom- 
ach, if  then  we  feel  no  hunger,  we  may  be  assured  that  the 
stomach  craves  no  food  because  it  cannot  digest  it.     How- 
ever long  it  may  have  been  without  food,  if  it  do  not  by  its 
hunger  declare  its  readiness  and   ability  to  convert  it  into 
nutriment  for  the  blood,  it  is  useless  to  eat.     It  is  even  worse 
than  useless;  for  whatever  is  then  eaten  cannot  be  changed 
to  pulpy  chyme,  nor  to  milky  chyle,  nor  can  the  lacteals  ex- 
tract from  it  nourishment  to  feed  the  exhausted  blood,  or  the 
wasted  body.     Food,  then,  eaten  when  we  are  not  hungry, 
gives  weakness  and  oppression,  and  not  strength  and  vigor. 
It  causes  pain  rather  than  the  feeling  of  comfort,  that  follows 
or  accompanies  good  digestion. 

93.  On  the  other  hand,  appetite  is  not  always  evidence  of 
digestive  power.     In  some  states  of  dyspepsia  there  is  a  vo- 
racious desire  of  food,  without  corresponding  power  in  the 
stomach  to  digest  it.     There  is  sometimes   a  diseased  and 
continual  irritation  in  this  organ,  which  suggests  to  the  brain 
the  want  of  food  as  the  only  means  of  allaying   it.     If  food, 
in  these  cases,  be  eaten  according  to  the  appetite,  —  or  if,  in 
some  cases,  any  food  be  taken,  however  urgent  the  hunger, — 


DIGESTION    AND    FOOD.  49 

indigestion  and  pain  will  surely  follow.  Very  frequently, 
during  convalescence  from  fevers,  the  appetite  returns  before 
the  power  of  digestion.  The  body  is  wasted  with  disease, 
and  wants  a  great  quantity  of  nourishment  to  restore  its  loss. 
The  fever  has  gone ;  the  stomach  is  free  from  nausea,  but 
yet  it  is  uneasy,  and  craves  a.  large  supply  of  nutritious  food. 
But  it  has  not  regained  its  full  strength.  It  can  no  more 
digest  a  full  allowance  of  hearty  food  than  the  muscles  or 
limbs  can  perform  the  full  day's  labor  of  a  man  in  health.  If 
the  convalescent  should  eat  a  strong  man's  food,  as  appetite 
suggests,  pain  and  weariness  will  fall  upon  his  digestive  or- 
gans as  inevitably  as  they  would  upon  his  limbs  if  he  should 
do  a  strong  man's  work. 

94.  Appetite  and  taste  are  not  the  same.     It  is  a  mistake 
in  our  self-management  to  confound  the  one*with  the  other. 
One  is  a  desire  for  food  corresponding  to  the  wants  of  the 
system  ;  the  other  is  mere  pleasantness  of  the  food  while  in 
the  mouth.     In  domestic  economy,  when  the  array  of  suc- 
cessive dishes  of  various  kinds  comes  before  us,  when  all  are 
delicious  and  tempting,  and  pleasant  to  the  palate,  there  is 
danger  of  eating  of  one,  and  then  another,  to  gratify  the  taste, 
even  after  appetite  has  been  satisfied.    It  is,  therefore,  impor- 
tant to  distinguish  between   the  sensation   of  the   stomach 
which  implies  the  want  of  nutriment,  and  which  is  real  hun- 
ger, and  that  mere  sensation  of  the   mouth  which  implies 
merely  the  want  of  something  pleasant  to  the  palate,  and 
which  is  factitious  hunger. 

95.  There  are  remarkable  instances  of  absence  of  appe- 
tite under  disease  or  excitement.      Sometimes  persons  in  a 
high  state  of  mania,  with  the  mind  violently  excited  or  ab- 
sorbed, have  endured  entire  abstinence  from  food  or  drink  for 
three  days.     During  this  time,  they  could  not  be  persuaded 
to  take  a  morsel  to  eat  or  a  drop  of  fluid.     In  these  and  sim- 
ilar cases,  there  were  undoubtedly  want  of  nourishment  in  the 
body,  and  power  of  digestion  in  the  stomach.     The  appetite 
was  suspended,  because  the  brain  had  its  attention  intently 
fixed  upon  its  delusions  and  distress.     But  when  the  excite- 

5 


50  PHYSIOLOGY    AND    HEALTH. 

ment  was  calmed  and  the  distress  alleviated,  the  sufferer  was 
persuaded  to  eat,  and  ate  with  the  usual  freedom,  and  digested 
with  the  usual  ease  and  comfort. 

96.  Some  extreme  instances  of  this  are  on  record.     "One 
is  published  in  the  Edinburgh  Medical  Essays  for  1720,  of  a 
young  lady  about  sixteen  years  of  age,  who,  in  consequence 
of  the  sudden  death  of  an  indulgent  father,  was  thrown  into  a 
state  of  tetanus,  or  rigidity  of  all  the   muscles   of  the  body, 
and  especially  those  of  swallowing,  accompanied  with  a  total 
loss  of  desire  for  food,  as  well  as  incapacity  for  swallowing  it, 
for  two  long  and  successive  periods  of  time — in  the  first  in- 
stance for  thirty-four,  and  in  the  second  for  fifty-four  days; 
during  all  which  time  of  her  first  and  second  fastings,  she 
declared  she  had  no  sense  of  hunger  or  thirst,  and  when  they 
were  over  she  had  not  lost  much  flesh."  * 

97.  The  celebrated  Miss  Ann  Moore,  of  Tutbury,  Eng- 
land, lived  for  some  years  on  so  little  food,  that  she  was  sup- 
posed to  live   entirely  without  it ;  and  she  even  pretended 
that  she  was  able  to  live  without  any  food  whatever.     A 
woman,  in  consequence  of  lockjaw,  swallowed  nothing  but 
a  very  little  cold  water  for  four  years;  and  for  twelve  .years 
afterward  took  no  more  food  than  is  sufficient  for  a  child 
two  years  old. 


CHAPTER  XL 

Great  Eaters. —  Causes  of  enormous  Appetite  and  Eating.  —  Stom- 
ach distended  by  Over-eating.  —  Hunger  recurs  when  Blood  wants 
more  Chyle.  —  Intervals  between  Meals  vary  with  Circumstances 
—  Disturbance  of  the  usual  Hours  of  Eating  disturbs  Digestion  — 
Intervals  of  Meals. 

98.    ON  the  contrary,  there  are  instances  of  persons  who 
from  disease  or  perverse  habit,  have   acquired   an  extraordi- 

*  Good's  Nosology,  p.  1G,   note. 


DIGESTION     AND   FOOD.  51 

nary  and  almost  insatiable  appetite  for  food.  With  them 
hunger  seems  to  be  ever  present.  The  stomach  full  of  food 
hardly  allays  the  desire  for  more,  or  only  suspends  it  for  a 
short  time.  A  case  is  recorded,  in  the  "  Philosophical  Trans- 
actions," of  "  a  boy  of  twelve  years  of  age,  who  had  so 
strong  a  craving  that  he  would  gnaw  his  own  flesh  when  not 
supplied  with  food.  When  awake,  he  was  constantly  devour- 
ing, though-  whatever  he  swallowed  was  soon  afterwards 
rejected.  The  food  given  him  consisted  of  bread,  meat, 
beer,  milk,  water,  butter,  cheese,  sugar,  treacle,  (molasses,) 
puddings,  pies,  fruits,  broth,  potatoes ;  and  of  these  he  swal- 
lowed in  six  successive  days  three  hundred  and  eighty-four 
pounds  two  ounces,  avoirdupois  —  being  sixty-four  pounds 
a  day  on  an  average.  The  disease  continued  for  one  year."  * 

99.  Idiots  have  generally  an  inordinate  appetite,  which 
they  indulge  if  they  have  opportunity.     In  1846,  Dr.  Sam- 
uel Gr.  Howe,  chairman  of  a  commission  appointed  by  the 
government  of  Massachusetts  for  the  purpose,  ascertained 
the  measure  of  appetite  and  habits  of  four  hundred   and 
thirty-two  idiotic  children  and  youths.    In  comparison  with 
others  of  their  age,  twenty-four  of  these  ate  less  than  the  av- 
erage ;  about  one  fifth  ate  the  average  quantity ;  about  one 
fourth  ate  from  ten  to  forty  per  cent,  more ;  about  the  same 
number  ate  from  fifty  to  ninety  per  cent,  more  than  others ; 
and   rather  more  than  one  quarter  ate  double  the  usual 
amount,  and  some  of  these  ate  in  still  larger  proportions. 

100.  This  enormous    appetite   does   not   always   depend 
upon  the  wants  of  the  system,  but  in  some  cases,  as  in  the 
boy,  §  98,  upon  disease.     In  others  it  is  caused  by  indulging 
the  perverse  habit  of  voracious  eating.     Great  eaters  feel  the 
want  of  a  large  quantity  in  the  stomach.     They  are  no  bet- 
ter nourished  than  those  who  eat  less  ;  but,  without  a  great 
supply,  they  feel  hollow,  faint,  and  languid.     The  stomach, 
being  used  to  this  great  distention,  does  not  act  easily  upon 
a  small  quantity.     In  some  persons,  the  stomach,  being  once 
distended,  does  not  recover  its  original  size.     Dr.   Darwin 
states   that  "  a  woman  near   Litchfield,  England,    who    ate 

*  Good's  .Nosology,  p.  16,  note. 


53  PHYSIOLOGY    AND    HEALTH. 

much  animal  and  vegetable  food  for  a  wager,  affirmed  that, 
since  distending  her  stomach  so  much,  she  had  never  felt 
herself  satisfied  with  food,  and  had  in  general  taken  twice 
as  much  at  a  meal  as  she  had  been  accustomed  to  before  she 
ate  so  much  for  a  wager."  * 

101.  This  is  an  extraordinary  instance  of  extreme  disten- 
tion  of  the  stomach ;    but  it  is  not  unusual   to  find    similar 
conditions,  though  in  a  less  degree,  produced  by  smaller  er- 
rors of  the  same  kind.     This  unnatural  state  of  the  stomach 
comes    oftener   from   a  long  and  gradually-increased   indul- 
gence in  great  eating,  amounting  sometimes  to  gluttony,  than 
from  a  single  gormandizing,  as  in  the  case  of  the  woman 
stated  in  the  last  section.     But  it  is  an  error  that  creeps  on 
very  insidiously,  and  with  a  seemingly  good  cause;  and  one 
who  begins  to  trespass  in  this  way  is  in  danger  of  repeating 
the  mistake,  and  of  increasing  the  evil  continually,  without 
suspecting  he  is  doing  any  more  than  obeying  the  natural 
laws  of  his  sensations,  and  supplying  his  proper  wants. 

102.  As  soon  as  any  of  the  food  is  digested  and  reduced 
to  chyme,  and  sent  into  the  duodenum,  the  innumerable  ab- 
sorbents commence  their  work  of  absorbing  or  taking  up  the 
chyle  —  the  nutritious  portion  — and  carrying  it  to  the  veins. 
They  continue  this  work  for  several  hours,  more  or  less,  ac- 
cording to  the  fulness  of  the  storehouse  of  nutriment;   and 
during  this  time,  they  replenish  the  waste  of  the  blood,  and 
enable  it  to  supply  the  wants  of  the  whole  body.     After  a 
varying  period  of  some  hours,  the  quantity  of  chyle  is  ex- 
hausted in  the  alimentary  canal,  and  can  furnish  no  more 
material  for  the  blood,  and  the  blood  can  no  longer  meet  the 
demands   of  the   wasting    flesh.     Then    there  is   a  want  of 
more  and  new  nutriment  —  a  craving  for  food  in  the  stomach, 
and   a  consequent  sensation  of  hunger,  and  we  need  to  eat 
again. 

103.  The  period  for  the  return  of  appetite,  or  the  proper 
interval  between  the  hours   of  eating,   depends   upon  many 
circumstances  and  conditions,  such  as  the  temperament,  the 

*  Zoonomia,  Vol.  II.,  p.  107. 


DIGESTION  AND  FOOD.  53 

age,  and  the  habits  of  the  person,  and  the  quantity  and  di- 
gestibility of  the  food  previously  eaten.  The  nutriment 
would  be  earlier  exhausted,  and  hunger  sooner  return,  after  a 
light  meal  of  innutritions  food,  than  after  a  full  meal  of  rich 
food.  The  young  and  growing  need  food  oftener  than  the 
mature  arid  full-grown,  and  the  convalescent  oftener  than 
the  permanently  healthy.  The  expenditure  of  life  and  the 
waste  of  particles  are  more  rapid  when  we  are  in  motion 
than  when  we  are  still.  Consequently  the  active  and  labori- 
ous are  sooner  exhausted,  and  need  to  be  earlier  recruited, 
and  should  eat  more  frequently  than  the  slow  and  indolent. 
The  sanguine  and  the  nervous,  for  the  same  reason,  are  mere 
impatient  of  hunger  than  the  lymphatic  and  dull. 

104. .  The  return  of  appetite  is  very  easily  trained  to  reg- 
ular habits,  so  that  it  comes  at  about  the  usual  time  of  eating  ; 
and  until  that  hour,  whatever  it  may  be,  hunger  is  not  felt. 
At  the  usual  hour  of  eating,  appetite  becomes  perceptible, 
and,  if  not  then  gratified,  it  may  become  urgent;  or  some- 
times it  ceases  till  the  next  time  of  eating.  The  stomach, 
being  trained  to  observe  these  hours,  accommodates  its  wants 
to  the  periods  of  supply.  Those  who  dine  at  twelve  feel  the 
want  of  food  at  that  hour ;  while  those  who  dine  later,  what- 
ever may  be  the  season,  are  not  often  disturbed  with  hunger 
until  their  usual  time  of  eating  comes  round,  and  then  they 
feel  the  want  of  food. 

105.  This  power  of  the  stomach  to  accommodate  itself  to 
the  habits  of  life,  is  not  only  manifested  in  different  persons, 
who  have  been  differently  educated  from  the  beginning,  but 
it  is  shown  in  the  same  individual  at  different  times.     We 
not  unfrequently  see  an  entire  change  of  habits  of  the  same 
stomach,  arising  from  change  of  manner  of  life. 

106.  Some  have  always  been  accustomed  to  dine  at  twelve, 
and  always  felt  hungry  at  that  hour.     Suddenly,  they  change 
their  residence  and  their  hour  of  eating,  and  wait  till  one  or 
two  o'clock  for  their  dinner.     The  stomach  does  not  change 
its  habits  and  wants  so  speedily.     At  first,  and  for  some  time, 
the  appetite  returns  at  the  former  hour  of  indulgence,  and 

5* 


54  PHYSIOLOGY   AND   HEALTH. 

waits  impatiently  for  its  food  ;  but  gradually  it  accommodates 
its  wants  to  the  new  regulation,  and  hunger  waits  quietly  till 
the  newly  adopted  hour.  Again,  the  same  persons  have  sud- 
denly returned  to  their  early  hours,  but  the  stomach  does  not 
go  back  so  readily ;  at  first,  it  was  not  in  want  of  food  at 
twelve;  but  in  a  short  period,  finding  its  supply  come  early, 
it  manifested  an  early  want,  and  became  hungry  at  twelve. 

107.  Whatever  the  accustomed  hours  of  eating  may  be, 
the  stomach  does  not  bear  sudden  changes,  not  even  for  a  sin- 
gle meal,  without  some  complaint.    One's  appetite  returns  at 
established  periods ;  then  his  stomach  craves  food,  and  the 
gastric  juice  is  ready  to  flow  and  dissolve  it.     If  this  want 
is  gratified,  his  dinner  is  digested  easily,  and  he  feels  com- 
fortable, and  prepared  for  business  during  the  afternoon. 
But  if,  for  any  cause,  he  varies  from  his  regular  habit,  and 
eats  at  a  later  or  an  earlier  hour,  his  digestion  is  not  so 
easy,  and  his  body  and  mind  are  not  so  free  for  labor. 

108.  A  gentleman,  being  one  day  occupied  abroad,  did 
not  return  to  his  dinner  until  three  o'clock.     He  felt  more 
hungry  than  usual.     But,  after  he  had  eaten,  his  stomach 
reminded  him  that  it  did  not  perform  its  work  with  its  cus- 
tomary ease.     His  body  was  not  so  light  and  buoyant,  his 
brain  was  not  so  clear,  as  usual ;  he  could  not  apply  his 
mind  with  its  accustomed  energy  to  its  work.    And  the  re- 
sult of  the  afternoon's  labors  was  less  than  on  other  days. 
The  same  has  generally  happened  at  other  times  when  he 
has  postponed  bis  dinner  beyond  its  accustomed  hour.    He 
feels  the  same  loss  of  energy  and  of  command  of  his  powers 
whenever  he  anticipates  the  hour  and  dines  at  twelve.     If 
he  had  been  a  mechanic,  he  would  have  had  the  same  dif- 
ference in  the  precision  and  success  with  which  he  could 
use  his  tools ;  or,  if  he  had  been  a  farmer,  there  would  have 
been  the  same  failure  in  the  energy  and  effect  of  wielding 
the  axe,  swinging  the  scythe,  or  striking  with  the  hoe,  after 
such  a  disturbance  of  the  hours  of  eating. 

109.  Some  families  have  no  regular  hours  of  eating. 
They  eat  whenever  it  suits  the  convenience  of  the  cooks  to 


DIGESTION   AND   FOOD.  55 

prepare  the  meals,  or  of  the  household  to  cat  them.  These 
are  varied,  and  often  very  widely,  to  meet  the  plans  and  the 
accidents  of  business.  These  people  dine  sometimes  very 
late,  and  at  other  times  very  early.  There  are  many  em- 
ployed in  cities  at  a  distance  from  their  homes.  They  do 
not  return  at  noon,  nor  do  they  dine  at  any  regular  boarding 
place;  but  they  eat  at  eating-houses,  at  any  hour,  when  the 
business  of  their  shops,  their  stores,  or  their  offices,  gives  them 
leisure.  Occasionally,  for  want  of  time,  they  omit  their 
dinner  entirely.  All  these  irregular  habits  of  eating  disturb 
their  regular  habits  of  digestion,  and  consequently  leave  them 
with  somewhat  less  power  of  application  and  labor  for  the 
next  succeeding  hours. 

110.  In  general,  the  intervals  of  the  meals,  during  the 
active  part  of  the  day,  should  not  be  more  than  six  or  seven 
hours.  Dinner  should  follow  the  morning  meal,  and  supper 
should  follow  the  noon  meal,  within  this  period.  The  fre- 
quency of  eating  should  follow  the  law  of  appetite,  described 
in  §§  102,  103,  p.  52;  and,  regarding  this  law,  children  and 
laborers  should  have  shorter  intervals,  and  eat  more  fre- 
quently than  the  mature  and  the  inactive. 


CHAPTER   XII. 

Breakfast  should  be  soon  after  rising.  —  If  it  be  late,  a  Lunch  should 
be  taken  early  in  the  Morning.  —  Health  better  sustained  when 
full.  —  Breakfast  should  be  before  Labor  or  Exposure.  —  Hour  of 
Dinner.  —  Interval  between  Breakfast  and  Dinner.  —  Forenoon 
Lunch  good  in  some  Cases.  — Needed  by  those  who  breakfast 
early  and  dine  late.  —  Night  Suppers  injurious.  —  Summary  of 
Meals. 

111.  DURING  the  hours  of  sleep,  there  is  no  action  of  the 
body,  and  comparatively  little  waste ;  therefore  the  interval 
between  the  evening  and  the  morning  meal  may  be  longer 
than  the  interval  between  the  meals  which  are  taken  in  the 
active  part  of  the  day.  Yet  the  store  of  nutriment  in  the 


-4 

56  PHYSIOLOGY    ANIX  HEALTH. 

digestive  organs  and  the  blood-vessels  becomes  exhausted 
during  the  night,  and  the  system  needs  more  food  before 
any  considerable  amount  of  action  is  undertaken  in  the 
morning;  for  the  frame  is  not  then  prepared  to  bear  any 
more  drafts,  and  it  must  be  recruited  before  it  can  undergo 
any  severe  labor.  The  breakfast  should  therefore  be  taken 
soon,  within  an  hour  after  rising.  This  is  especially  requi- 
site for  invalids,  who  have  not  much  strength,  and  but  little 
power  of  endurance. 

112.  When  the  morning  meal  is  not  to  be  eaten  early, 
some  light  refreshment  at  the  time  of  rising  will  meet  the 
immediate  wants  of  the   system,   and   sustain  it  during  the 
morning  exercise.     It  is   well,   then,   if  some    considerable 
time  is  to  elapse  between  rising  and  breakfast,  to  take  some 
food  early.     This  is  a  common  custom  among  the  Creoles 
of  Louisiana  and  the  inhabitants  of  Cuba,  and  some  classes 
of  people  in  France.     These  have  coffee,  fruit,  or  other  light 
food  sent  to  their    sleeping-rooms,    sometimes    before,   and 
sometimes  after  rising,  which,  they  think,  enables  them  the 
better  to  sustain  any  fatigue  before  the  regular  breakfast  is 
given  them. 

113.  The  animal  system  sustains   all   action,  labor,   and 
exposure  best  when  it  is  well  nourished.     When   the   nutri- 
ment fails,  it  becomes  sooner  fatigued,  and  more  susceptible 
of  pain;  and,  besides  this,  it  is  more  liable  to  suffer  from 
any  causes,  which  would  impair  its  soundness  or  diminish 
its  vitality.     The  contagion  of  disease,  the  infection  of  fever, 
whatever  may  bring  on  disorder,  act  more  readily  and  pow- 
erfully on  the  hungry,  and  on  those  who  are  badly  nourished, 
than  on  those  who  are  well  fed.     We  are  better  able  to  resist 
the  influence  of  cold,  and  to  maintain  the  natural  temperature 
of  the  body,  when  we  are  full,  than  when  we  are  fasting. 

114.  All  these  causes  of  disorder  or  suffering  act  upon 
the  human  constitution  with  more  destructive  force  before 
breakfast   than   afterward.     On    this   account,  all    who   are 
about   to  expose  themselves  to  any  of  these  morbid  influ- 
ences,   to  contagion  or   infection    of  disease,    or    to    such 


DIGESTION 

exhalations  of  marshy  countries  as  produce  fever  and  ague 
or  other  malady,  should  eat  their  breakfast  before  going 
abroad.  Travellers  and  others,  who  go  abroad  in  winter, 
or  in  stormy  weather,  will  maintain  their  heat  better  and 
defend  themselves  more  effectually  against  the  elements,  if 
they  breakfast  before  they  go  out.  But  if  they  go  out  in  the 
morning  hungry,  they  suffer  much  more  from  chills  and 
dampness,  and  are  in  greater  danger  of  taking  cold. 

115.  If  this  precaution  of  early  eating  be  requisite  for 
the  healthy    and  the  robust,    it    is    much   more    so  for  the 
feeble  and  the  invalid.     Inasmuch  as  those,  whose  strength 
and  vitality  are  in  any  way  reduced  below  the  average  stand- 
ard, are  more   susceptible  of  disorder  from   any  disturbing 
cause,  and  are  more  easily  fatigued  with  labor,  it  is  more 
necessary  for  them  than  for  others  to  strengthen  and  defend 
themselves  with  the  early  morning  refreshment,  before  they 
engage  in  laborious  occupation,  or  expose  themselves  to  cold 
or  infection. 

1 16.  The  time  of  the  dinner  differs  very  materially  in  vari- 
ous nations,  and  among  people  in  different  places  of  the  same 
nation.     Three  hundred  years  ago,  the  king  of  Englapd  and 
his  court  dined  at  eleven.     Some  of  the  nobility,  previous  to 
that  time,  breakfasted  at  seven,  dined  at  eleven,  and  supped 
at    four.     More    recently,    both    in    America    and    Europe, 
twelve  at  noon  was  the  established  hour  ;  and  at  present,  in 
the  rural   districts,  almost  every  where,  this  dining  hour  is 
still  observed  ;  while  in  towns  and  cities  the  time  varies  from 
one  to  six  or  seven.        But,   in   families  who  dine  so  late, 
breakfast  is  also  late,  and  the  interval  between  the  first  and 
second  meal  is  not  so  wide  as  the  lateness  of  the  dining  hour 
would  seem  to  indicate.     In  about  five  or  six  hours  after  the 
morning  meal,  the  appetite  returns,  and  the  system  calls  for 
new  refreshment.     This  is  the  true  guide  for  the  time  of 
dining.     Whatever  may  be  the  hour  of  breakfast,  not  more 
than  about  six  or  seven  hours  should  elapse    before  the  sys- 
tem is  again  refreshed  with  food. 

117.  In  some  of  the  European  cities,  breakfast  is  suffi- 


58  PHYSIOLOGY    AND    HEALTH. 

ciently  early,  but  the  dinner  is  taken  as  late  as  six  or  seven 
o'clock  in  the  evening.  This  habit  leaves  an  interval  of 
eight  to  ten  hours  between  the  first  and  second  meals,  which 
is  a  much  longer  space  for  fasting  than  the  time  specified  in 
the  last  section,  and  longer  than  the  system  can  well  endure 
without  suffering  from  want  of  nutriment.  Many  —  probably 
most  of  those  who  dine  so  late  —  remedy  this  difficulty  by 
interposing  a  lunch  between  the  first  and  second  meal  in 
the  day.  This  is,  with  most  people,  a  light  meal,  and  in- 
tended merely  to  sustain  nature  through  the  long  interval 
of  the  morning  and  noon ;  but  with  some  it  is  composed  of 
heavy  and  substantial  food,  such  as  would  ordinarily  be 
taken  for  dinner. 

118.  A  lady  went  from  Boston,  in  September,   1846,  to 
London.     Her  usual  "dining  hour  had  been  two,  at  home;  but, 
in  London,  it  was  suddenly  changed  to  six  or  seven  o'clock. 
Her  morning  meal  was  also  postponed  somewhat;  yet  the  in- 
terval between  these  was  several  hours  longer  than  she  had 
been  accustomed  to.     In  a  few  weeks,  she  suffered  materi- 
ally in  health,  and  became  much  debilitated,  and  consulted 
a  physician,   who  advised  a  lunch  to  be  taken  in  the  fore- 
noon.    Following  his  advice,  she  soon  recovered  her  wonted 
health  and  strength.     A  similar  case  occurred  in  New  Or- 
leans.    A  friend  suffered  in  the  same  way,  from  the  same 
cause,  and  was  restored  by  a  similar  change  in  his  hours  of 
meals. 

119.  Growing   children,    and    persons    recovering    from 
sickness,  and  men  engaged  in  very  hard  labor,  may  do  well 
to  lake  this  forenoon  lunch,  even  if  the  interval  between  the 
morning  and  noon 'meal  be  not  more  than  six  or  seven  hours. 
And  healthy  men,  in  ordinary  pursuits,  would  do  it  with  ad- 
vantage, if  they  breakfast  early  and  dine  very  late.     But  for 
mature  persons,  in  good  health,  who  are   not   engaged   in 
very   hard    labor,    and    whose  dinner    is    not  delayed    more 
.than  six  or  seven  hours  from  the  breakfast,  the  stomach  is 
better  if  at  rest  until  the  hour  for  the  regular  meal  comes 
round  at  noon. 


DIGESTION    AND    FOOD.  59 

120.  The  supper  is  usually  a  lighter  meal,  and  is  needed 
for   all   who  have  not  already  eaten  three  times.     It  is  the 
almost  universal  custom  of  the  civilized  nations  to  eat  three 
times  a  day.     Remembering  the  rule  before  stated,  (§  110, 
p.  55,)  that  not   more   than   six  or   seven    hours  of    active 
life  should  elapse  before  the  refreshment  of  food,  and  that  it 
should  not  usually  be  taken  oftener  than  this,  it  is  easy  to 
determine  whether  any  supper  should  be  taken  after  dinner 
or  not.     If  the  dinner  be  as  late  as  six  or  seven  o'clock,  and 
there  has  been  a  lunch  taken  in  the  forenoon  or  at  noon,  the 
fourth  meal  will  be  unnecessary.     When  the  dinner  is  at  or 
near  night,  so  late  that  there  will  be  not  more  than  four  or 
five  hours  between  this  meal  and  bed-time,  then  the  supper, 
if  taken  before  sleeping,  would  be  not  only  needless,  but  inju- 
rious.    It  is  not  then  wanted  for  nutrition,  a»d  the  stomach 
is  not  in  a  condition  to  digest  it.     The  supper,  therefore, 
should  depend  upon  the  distance  of  the  sleeping  hours  from 
the  dinner.     So  that  he  who  dines  at  twelve  and  retires  at 
nine,  and  he  who  dines  at  seven  and  retires  at  four,  both 
equally  need  the  evening  or  the  night  meal. 

121.  But    supper    should    be   eaten   usually   about   three 
hours  or  more  before  sleeping.     Sleep  is  the  rest  of  all  the 
voluntary  powers;  then  nothing  but  the  lungs  and  the  heart 
keep   in   motion ;    all  the  others  are  still.     The    mind,  the 
feelings    and    the    affections,  the    brain,  the   muscular    and 
digestive  organs,  all  need  and  enjoy  this  rest.     If  any  of  the 
organs  or  powers  are  riot  permitted  to  repose,  the  sleep  is 
not  profound;  the  rest  is  not  entire.     If,  then,  we  eat  so  late 
that  the  food  be  not  digested  before  we  retire  to  our  beds,  the 
digestion  is  still  going  on  while  we  attempt  to  sleep,  and  the 
sleep  is  disturbed  by  it;  then  dreams  —  sometimes  distressing 
dreams  —  oppress  and  weary  us,  and  the  body  and  mind  are 
not   refreshed    completely    for    the    following    day's    labor. 
Second  suppers  are  therefore  injurious. 

122.  The  general  custom  of  three  meals  a  day  —  a  good 
breakfast  soon  after  rising  in  the  mornino-,  a  fuller  and  more 

o  rt* 

nutritious  meal  near  the  middle  of  the  active  part  of  the^day, 


60  PHYSIOLOGY    AND    HEALTH. 

and  a  lighter  meal  a  few  hours  before  sleeping  —  meets  the 
wants  of  the  body,  and  corresponds  with  the  powers  of  diges- 
tion. But  when  we  add  to  these,  lunches  during  the  day, 
or  take  a  supper  of  feasting  for  hospitality  or  self-indulgence 
at  night,  we  overstep  the  demands  for  nourishment,  and 
overtask  the  powers  of  digestion,  and  prevent  the  full, 
refreshing  effects  of  sleep  at  night. 


CHAPTER    XIII. 

Quantity  of  Food.  — Fleshy  Persons  not  always  great  Eaters.  —  Lean 
Persons  not  always  small  Eaters.  —  Action  causes  Changes  of  Par- 
ticles.—  Laborers  eat  more  than  the  Sedentary. 

123.  THE  quantity  of  food,  as  we  shall  see  hereafter,  is 
not  to  be  governed  by  a  fixed  law.     Men  differ  in  their 
wants,  and  their  necessities,  and  their  powers.    Dr.  John  C. 
Dalton,  after  making  a  series  of  experiments  in  diet  and  nu- 
trition, says  he  "  found  that  the  entire  quantity  of  food  re- 
quired during  twenty-four  hours  by  a  man  in  full  health,  and 
taking  free  exercise  in  the  open  air,  is  as  follows :  — 

Meat, 16  ounces,  or  ....  I'OO  Ib. 

Bread, 19       "    . 1-19. 

Butter  or  fat,  .  .     3£     " '22. 

Water, 52  fluid  oz., 3'25  pints.'"* 

124.  The  seamen  in  the  British  navy  are  allowed  1  Ib. 
bread,  1  Ib.  fresh  meat,  £  Ib.  vegetables ;  and,  when  fresh 
meat  and  vegetables  are  not  given,  £  Ib.  salt  meat  and  f-  Ib. 
flour   are   allowed,  being  40  oz.  solid  food   for  each  day's 
support.     The  dietary  for  emigrants  going  from  Great  Britain 
to  the   East  Indies   and   New  Holland   gives  9  oz.  animal 
food,  12  oz.  bread,  4  oz.  flour,  2  oz.  rice,  1  oz.  raisins;  in 
all,  28  oz.  per  day.     The  soldiers  of  the  army  of  the  United 
States  are  allowed  to  have  f  Ib.  pork  or  bacon,  or  1£  Ib.  beef, 

*  Human  Physiology,  3d  ed.  p.  113. 


DIGESTION     AND    FOOD.  61 

fresh  or  salt,  18  oz.  bread  or  flour,  or  12  oz.  hard  bread,  or 
l£  Ib.  corn  meal,  a  day  besides  8  qts.  of  peas  or  beans,  or  10 
Ibs.  of  rice,  for  every  hundred  days. 

125.  The,  quantity  of  food  must  vary  with  the  habits  of 
the  individual,  and  with  the  energy  and  quantity  of  exercise. 
Some   have  a   much  greater   nutritive   power    than    others 
Some  extract  more  nutritive  chyle  from  a  given  amount  of 
food   than    others.     Fleshy   persons    are   not    always   great 
eaters,  nor  are  all  lean  persons  proportionately  limited  in 
their  quantity  of  food.     On  the  contrary,  there   are  many 
instances  of  great  corpulence  connected  with  an  extremely 
small  diet,  and  some  cases  where  the  greatest  temperance  in 
food  does  not  prevent  or  diminish  the  fatness.     On  the  other 
hand,  there  are  some  persons  whose  appetite  is  ever  ready, 
and  digestion  apparently  good,  and  who  consume  much  more 
than  the  average  quantity  of  aliment,  and  yet  are  miserably 
lean. 

126.  A  young  woman,  whose  body  was  full,  round,  and 
almost  fat,  came  under  my  observation  a  few  years  ago,  on 
account  of  neuralgia.     The  pain  was,  for  a  long  time,  fixed 
in  the  stomach,  and  then  she  could  only  eat  a  single  cracker, 
or  an  equal  amount  of  bread,  weighing  less  than  one  ounce 
a  day.     Yet  her  nutritive  powers  were  so  good,  that,  with 
this  small  quantity  of  food,  she  maintained  her  full  condition, 
and  showed  no  sensible  loss  of  flesh.     She  continued  this 
spare  diet  for  about  six  weeks,  and,  in  all  this  time,  retained 
her  healthy  plumpness  of  form.     She  was  not  strong,  and 
yet  she  was  not  very  weak.     She  was  not  confined  to  her 
bed,  nor  to  her  chamber,  but  was  able  to  be  about  the  house, 
and  perform  the  light  household  work.     In  her  best  state  of 
health,  she  was  a  small  eater;  but  she  was  then  strong  and 
vigorous,  active  and  fleshy. 

127.  The  requisite  quantity  of  nutriment  varies  more  with 
quantity  and   energy  of  action  which  the  system  is  called 
upon  to  sustain.     All  motion  is  connected  with  waste  from 
the  body ;  the  vitalized  particles  exhaust  their  vitality  in  the 
process  of  action,  and  a  change  then  takes  place.     The  old 

6 


62  PHYSIOLOGY   AND   HEALTH. 

and  exhausted  particles,  having  lost  their  living  principle,  are 
then  removed  from  their  places  in  the  tissues  of  the  body, 
and  thrown  into  the  veins,  and  thence  carried  away.  Their 
places  must  be  supplied  by  new  particles  from  the  blood, 
and  the  blood  receives  these  from  the  digested  food.  The 
body  of  the  laborer,  therefore,  undergoes  more  rapid  waste, 
and  needs  a  greater  and  more  frequent  supply  of  food,  than 
that  of  the  people  of  sedentary  habits,  or  idlers.  It  is  a  great 
mistake,  then,  to  suppose  that  all  men,  in  whatever  occupa- 
tion engaged,  should  eat  the  same  quantity  of  food.  The 
British  government  give  to  the  troops,  on  their  voyage  to  the 
East  Indies,  on  account  of  the  quietness  of  their  life,  30  per 
cent,  less  of  solid  food  than  to  the  sailors,  who  are  in  con- 
stant action  on  board  the  same  ships. 

128.  For   this  reason,  the  same  man  should  not  cat  the 
same  quantity  in  all  varieties  of  exercise.     At  one  period, 
he  may  be  very  laborious :  he  then  wants  more  food  than  at 
another  time,  when  he  may  be  engaged  in  lighter  employ- 
ment.    This  principle  ought  not  to  be   forgotten  by  those 
who  make  permanent  changes  in  their  occupations.   Change 
of  habits  presupposes    change   of  nutritive  wants.     If  the 
action  of  the  body  be  reduced,  there  is  a  reduction  of  waste, 
and    of  nutritive    want    and    digestive   power.     But,  unfor- 
tunately, the  appetite  is  not  readily  reduced,  nor  is  it  per- 
fectly easy  to  control  it  at  once.     But  this  is  necessary,  in 
order  to  prevent  indigestion. 

129.  xSome  young  men,  who  have  been  accustomed  to  active 
exercise,  or  even  hard  labor,  suddenly  change  their  occupa- 
tions.  They  leave  their  farms  or  their  workshops,  and  go  to 
school  or  to  college,  or  to  the  lighter  employment  of  cities. 
Their  habits  of  eating  have  been  very  properly  adapted  to 
their  habits  of  labor.     While  they  were  hard  workers,  they 
were  hearty  eaters.     Too  frequently,  their  full  diet  is  retained 
after  their  hard  labor  of  body  is  discontinued,  and  they  still 
eat  the  same  amount  of  food  as  before.     This  is  more  than 
the   system   now  requires,  and  more  than  the  stomach  can 
digest.     That  quantity,  which  was  no  more  than  sufficient  to 


DIGESTION   AND    FOOD.  63 

sustain  a  life  full  of  vigorous  and  laborious  action,  is  too 
much  for  the  inactive  and  sedentary  life,  and  even  becomes 
oppressive  and  injurious. 

130.  Hence  men  complain  of  indigestion  and  of  loss  of 
health  in  other  ways,  when  they  have  become  less  active. 
The  real  ground  of  difficulty  is  not  so  much  that  their  new 
occupations  are  necessarily  injurious  to  digestion,  as  that  the 
quantity,  and  often  the  quality,  of  food  is  not  adapted  to  their 
altered  habits.     In  the  new  occupation,  there  is  less  action, 
arid   consequently   less   waste,  and  of  course  less   use    and 
demand  for  food,  and,  necessarily  connected  with  these,  less 
digestive   power.     When    these   new    conditions    are    disre- 
garded, and  the  old  habits  of  eating  continued,  the  stomach 
is  overburdened,  and  dyspepsia  follows,  with  its  usual  train 
of  evils. 

131.  It  is  not  unfrequent  at  Cambridge  —  and  doubtless  it 
is  the  same  at  other  colleges  —  for  some  of  the  most  industri- 
ous students  to  leave  on  account  of  ill  health.     These  unfor- 
tunate invalids  are  more  among  the  older  than  among  the 
younger  members  of  the  classes.    And  the  reason  is  plain. 
Most  of  these  were  not  originally  destined  to  literary  pursuits, 
and  were  engaged,  in  their  earlier  years,  on  their  farms,  or 
in  their  workshops,  or  other  spheres  of  active  employment. 
They  were  generally  strong  and  healthy,  but,  having  a   de- 
cided inclination  for  the  study  of  books,  they  changed  their 
active  habits  of  body  for  the  quietness  of  the  student's  life. 
But  their  appetite  and  diet  continued  the  same,  and  thereby 
they  fell.     Others  were  younger,  and  went  through  college 
with  less  suffering  and  fewer  failures  of  health.     These  had 
never   been   laborious,  nor  had  they  acquired  the  habits  of 
eating  which  laboring  men  should  have.     Their  habits  were 
always  adapted  to  their  present  circumstances,  and   conse- 
quently they  were  spared,  at  least,  this  cause  of  ill  health. 

132.  Men  arid  women  who  have  reached  the  fulness  of 
stature,  cannot  safely  indulge  the  habits  of  eating  which  were 
proper  for  them  while  they  were  growing.     The  quantity  of 
food  which  was  necessary  to  supply  the  growth  in  youth,  is 


64  PHYSIOLOGY    AND    HEALTH. 

more  than  is  needed  in  mature  years.  And  not  only  is  it  not 
needed,  but  it  is  a  burden  to  the  system,  and  imposes  nn  in- 
jurious tax  upon  the  powers  of  the  stomach  to  digest  it.  As 
soon,  therefore,  as  the  body  ceases  to  grow,  the  diet  should 
be  reduced  from  the  fulness  of  youth,  and  accommodated  .to 
the  more  limited  wants,  of  the  system.  Convalescents,  very 
properly,  eat  a  greater  quantity  while  they  are  recovering  lost 
flesh,  in  order  to  meet  the  new  conditions,  and  supply  the 
new  wants  of  the  system ;  but  the  moment  they  have 
regained  their  usual  fulness,  they  should  return  to  their 
usual  diet. 


CHAPTER    XIV. 

Quantity  of  Food  determined  by  the  Wants  of  the  System  and  the 

digestive   Power.  —  Measured   thus  only  when  we  eat  slowly 

Each  one  must  judge  for  himself  how  much  he  shall  eat.  —  Excess 
of  Food  oppresses  and  weakens.  —  Due  Quantity  strengthens.  — 
Time  saved  by  hasty  Eating  more  than  lost  by  Oppression  after- 
ward.—  Rapid  Eating  at  Hotels  and  on  Steamboats. 

133.  IT  has  been  shown,  (§§  39,  40,  pp.  25,  26)  that,  when 
the  whole  system  is  in  good  health,  the  digestive  powers  of  the 
stomach  correspond  to  the  nutritive  wants  of  the  body ;  that, 
when  the  body  is  in  want  of  nourishment,  the  stomach  pre- 
pares, or  is  ready  to  prepare,  gastric  juice  sufficient  to  dissolve 
as  much  food  as  is  needed,  and  no  more;  and  that  this  quan- 
tity of  gastric  juice  gives  us  the  measure  of  the  food  which 
should  at  anytime  be  taken.     If  we  could  then  ascertain  this 
quantity  of  gastric  juice,  we  should   have   no  difficulty  in 
determining  the  requisite  amount  of  food.     In  St.   Martin 
(§  35,  p.  23)  the  flow  of  this  juice  could  be  seen  through  the 
aperture,  and  its  quantity  ascertained  ;  but  we  can  only  obtain 
this  knowledge  by  carefully  watching  our  own  sensations. 

134.  When  the  body  wants  nourishment,  and  the  stomach 
is  ready  to  pour  out  gastric  juice  and  digest  it,  there  is  a  sensa- 
tion of  hunger,  (<§  42,  p.  27;)  and  this  sensation  continues  as 


DIGESTION    AND    FOOD.  65 

long  as  there  is  any  of  this  gastric  juice  unoccupied  by  food, 
or  until  the  inner  coat  of  the  stomach  has  poured  out  as 
much  as  it  can  give  at  the  time.  So  long  as  this  sensation 
continues,  there  is  a  call  for  more  food,  and  more  can  be 
digested.  We  may  safely  eat,  then,  until  this  natural  appetite 
ceases,  provided  we  throw  the  food  into  the  stomach  no 
faster  than  the  digesting  fluid  is  ready  to  dissolve  it.  Mr.  D. 
(<$  43,  p.  '27)  did  not  even  eat  until  his  hunger  ceased ;  and 
yet  he  ate  more  than  his  gastric  juice  could  dissolve. 

135.  In  order,  then,  to  adapt  the  food  to  the  wants  of  the 
system  and  the  power  of  digestion,  we  must  eat  slowly ;  we 
must  masticate  each  morsel  patiently  and  thoroughly  in  the 
mouth,  waiting,  in  this  manner,  before  we  swallow  this,  until 
the  previous  morsel  has  had  time  to  combine  with  the  gastric 
juice  in  the  stomach      So  doing,  we  can  determine  whether 
that  organ  wants  or  is  prepared  for  another ;  and.  when  that 
demand  ceases,  we  can  suspend  the  eating.     Then  we  shall 
have  eaten  all  that  is  needed  for  nutrition,  and  no  more  than 
the  stomach  can  digest. 

136.  This   will  require  us  to  eat,  not  to  fulness,   as  is 
unhappily  too  commonly  done;  nor  even  to  satiety,  for  that 
would  overstep  the  wants  of  nature ;  but  merely  until  the 
demand  for  nutrition  ceases.     Dr.  Beaumont  says,  "  There 
seems  to  be  a  sense  of  perfect  intelligence  conveyed  to  the 
brain,  which,  in  health,  invariably  dictates  what  quantity  of 
aliment, (responding  to  the  sense  of  hunger  and  its  due  satis- 
faction) is  naturally  required  for  the  purposes  of  life,  and 
which,  if  noticed  and  properly  attended  to,  could  prove  the 
most  salutary  monitor  of  health  and  effectual  preventive  of 
disease.     It  is  not  the  sense  of  satiety ;  for  this  is  beyond  the 
point  of  healthful  indulgence,  and  is  Nature's  earliest  indica- 
tion of  an  abuse  and  overburden  of  her  powers  to  replenish 
the  system.     It  occurs  immediately  previous  to  this,  and  may 
be  known  by  its  pleasurable  sensations  of  perfect  satisfaction, 
ease,  and  quiescence  of  body  and    mind.     It  is  when    the 
stomach  says,  Enough.     It  is  distinguished  from  satiety  by 
difference  of  sensation;  the  latter  says,  Too  much." 

6* 


60  PHYSIOLOGY    AND   HEALTH. 

137.  The    wants    of    nutrition,    even    in    men     in    good 
health,   depend  upon  so  many  circumstances,  —  their  exer- 
cise, exposure,  and  their  temperament,  —  and  the  digestive 
powers  differ  so  widely  in  different  people,  that  we  could 
scarcely  find  two  who  require  exactly  the  same  quantity  of 
food,  nor  would  the  same  man  require  the  same  quantity  at 
all  times.     Therefore  it  is  impossible  to  prescribe  any  exact 
weight  or  measure,  which  all   should   eat.     But  every  one 
who  learns  the  principles  which  have  been  stated  here,  who 
examines  the  circumstances  of  his  own  life,  and  carefully 
watches  his  own  sensations,  will  be  better  able  to  determine 
how  much  he  shall  eat.     If  then,  he  faithfully  obeys  the  law 
of  nutrition,  and  applies  it  rigidly  to  his  own  self-management, 
he  will  not  err  in  his  diet. 

138.  When  a  man  eats  sufficiently,  and  no  more,  —  when 
his  stomach  has  received  no  more  than  it  can  easily  digest, — 
he  feels  refreshed  and  easy  ;  he  soon  becomes  light  and  buoy- 
ant, and  is  then  ready  to  recommence  his  active  business. 
But  when  the  stomach  has  more  than  it  can  easily  convert  into 
chyme,  it  is  oppressed  with  labor,  and  feels  a  dead  weight 
bearing  it  down.     All  the  energies  of  the  body  are  then  con- 
centrated in  the  effort  of  the  stomach  to  perform  its  extraor- 
dinary labor,  in  the  same  manner  as  all  the  energies  of  the 
system  are  concentrated  in  the  extraordinary  muscular  exer- 
tion, when  we  attempt  to  lift  great  weights,  or  to  run  a  race. 
While  the  digestive  organs,  or  the  muscles,  are  making  these 
great  exertions,  we  can  do  nothing  else ;  we  can  neither  use 
the  brain   and   think,   or   study,   or   calculate,  nor   can  the 
muscles  perform  any  other  labor. 

139.  As  much  food,  then,  as  the  system  needs  and  the 
stomach  can  digest,  gives  a  man  comfort,  strength,  and  ability 
to  apply  his  powers  to  business.     It  enables  him  to  use  his 
brain,  and  his   muscles,  and  his  bones  —  to  work  with   his 
hands,  his  feet,  and  his  mind.     But  all  excess  of  food  beyond 
this,  every  mouthful  more  than  is  needed  or  easily  dissolved, 
gives  weakness,  instead  of  strength,  for  business.     It  is  a  tax 
upon  the  vital  energies,  and  a  clog  upon  the  motions  of  the 


DIGESTION    AND    FOOD.  67 

body  and  the  actions  of  the  mind.  We  see  this,  in  a  remark- 
able degree,  in  the  glutton,  who,  after  his  dinner,  can  do 
nothing  but  digest.  He  can  neither  work  nor  think,  because 
ail  the  power  of  body  and  brain  are  concentrated  in  the 
stomach.  There  are  not  many  who  indulge  their  appetite  to 
this  extent,  and  suffer  so  much  in  consequence.  But  there 
are  many  who  err  in  a  lesser  degree.  They  are  not  gor- 
mandizers, yet  they  eat  too  much,  and  suffer  in  weakness 
precisely  in  the  ratio  of  their  error. 

140.  It  has  been  before  shown  (§  41,  p.  26)  that  rapid 
eaters  consume  more  than  they  need  or  can  digest.     Yet  many 
eat  rapidly,  in  order  to  gain  in  time.     They  imagine  that 
twenty  minutes  or  half  an  hour,  spent  at  their  table,  is  a 
waste  of  many  minutes,  which  they  might  employ  in  business 
or  labor.     They  masticate  little,  and  swallow*  morsel   after 
morsel   in  quick   succession,   and  soon   their   stomachs    are 
filled ;    and  then  they  hurry  back  to  their  employment,  in  the 
mistaken  confidence  that  they  have  gained  by  this  haste,  and 
that  they  shall  accomplish  so  much  the  more  by  thus  shorten- 
ing the  time  of  eating.     But  they  carry  with  them  a  load  that 
consumes  a  portion  of  their  strength,  which  they  might  other- 
wise   have   devoted    to   their    labor.     The    farmer    and    the 
mechanic  —  the  merchant  and  the  student  —  every  man  who 
wishes  to  accomplish  the  most  by  the  use  of  his  physical  or 
his  mental  powers  —  will  effect  his  purposes  the  most  suc- 
cessfully, by  eating  slowly  and  cautiously,  and  giving  ample 
time  to  the  table.     It  therefore  is  bad  economy  to  hasten  at 
our  meals. 

141.  An  industrious  merchant  of  Boston,  when  formerly 
engaged  in  business,  frequently  walked  a  quarter  of  a  mile, 
and  ate  his  dinner,  and  returned  to  his  counting-room  in 
fifteen  minutes;  and  was  then  pleased  that  he  lost  so  little 
time.     While  at  table,  he  swallowed  his  food  as  fast  as  pos- 
sible, giving  insufficient  time  to  his  mouth  for  mastication, 
and  as  little  to  his  stomach  to  mix  the  food  with  the  gastric 
juice;    and  yet  he  ate  too  much,   and  was  oppressed  after- 
wards.    He  gained  in  time,  but  he  lost  in  energy  and   in 


PHYSIOLOGY    AND    HEALTH. 

power  of  attending  to  his  affairs.  In  the  afternoon  he  was 
somewhat  heavy  —  his  brain  was  not  clear  —  he  was  indis- 
posed to  look  into  his  accounts,  or  to  talk  with  his  customers 
upon  matters  of  business;  and  he  accomplished  much  less 
during  the;  rest  of  the  day,  than  he  might  have  done  if  he 
had  allowed  himself  sufficient  time  for  his  dinner.  This  was 
the  first  result;  the  second  and  remoter  result  is  painful 
dyspepsia,  which  now,  after  years  of  error,  weighs  heavily 
upon  him. 

142.  It  is  common  to  notice  this  error  at  hotels,  where 
strangers  gather.  Travellers  seem  to  be  often  compelled, 
by  the  impatience  of  the  coach  or  the  railroad  car,  to 
swallow  their  hasty  meal  with  all  possible  speed ;  and,  unfor- 
tunately, they  too  often  continue  the  habit  when  the  apparent 
necessity  ceases.  The  same  hurry  at  meals  is  often  seen  in 
the  steamboats,  and  at  public  tables  in  the  cities.  In  steam- 
boats particularly,  where  the  passengers,  from  morning  till 
night,  have  nothing  to  do  but  to  eat,  there  is  commonly  man- 
ifested an  eager  haste  in  swallowing  food,  as  if  all  the 
minutes  spent  at  the  table  were  lost,  or  worse  than  lost,  and 
the  company  were  resolved  to  get  away  from  it  as  soon  as 
possible. 


CHAPTER    XV. 

Appetite  allowed  to  accompany  the  Duty  of  Eating.  —  Unwise  to  eat 
for  this  alone. —  We  eat  too  much  for  Appetite  alone,  and  make 
this  the  Means  of  Hospitality  and  social  Enjoyment. —  Children's 
Appetites  pampered.  —  All  Indulgence  of  mere  Appetite  followed 
by  Suffering. 

143.  IT  is  one  of  the  proofs  of  the  benevolence,  as  well  as 
the  wisdom,  of  the  generous  Creator,  that  whatever  duty  is 
required  of  us  by  the  necessities  of  our  nature,  is  also  made 
pleasant  in  the  performance.  Food  is  made  necessary  for 
the  support  of  the  body,  and  appetite  is  given  to  make  the 
taking  of  that  food  a  source  of  great  pleasure.  Here  are 


DIGESTION    AND    FOOD.  69 

two  principles  to  be  noticed  and  observed  :  1st,  that  we 
are  commanded  to  eat  as  much  food,  and  of  such  quality,  as 
the  stomach  can  easily  convert  into  the  material  for  the 
blood,  and  the  system  requires  for  its  nourishment;  2d,  that 
this  food  may  be  so  selected  and  compounded,  and  cooked 
in  such  a  manner,  as  to  be  agreeable  to  the  palate.  We  are 
not  only  allowed  by  the  law  of  our  being  to  enjoy  the  pleas- 
ures of  the  table,  but  there  are  encouragements  and  induce- 
ments held  out  for  us  to  obtain  this  enjoyment,  whenever  it 
is  consistent  with  the  first  duty. 

144.  But  it  is  plain  that  this  pleasure  of  the  appetite  is 
merely  the  accompaniment,  not  the  main  end,  of  eating,  and 
should,  therefore,  never  be  the  motive  for  this  act.     To  select 
our  food,  not  according  to  its  nutritive  power,  or  its  digesti- 
bility, but  according  to  its  acceptableness  to  fhe  palate, —  to 
eat  when  the  body   does  not  require  nourishment,  or,  after 
we  have  taken  sufficient  for  this  purpose,  to  eat  some  more 
for  the  indulgence  of  the  pleasure,  —  these  are  manifest  per- 
versions of  the  duty  required  of  us,  and   abuses    of  a   privi- 
lege granted  to  us.     It  would  seem  a  very  foolish  thing  in  a 
shipmaster  to  load  his  vessel,. not  with  the    freight   that    it 
can  carry  best,  or  which    is  wanted    at  the  port  of   desti- 
nation, but  with  that  which  is  the  pleasantest  to  load  ;  or  if, 
for   the  same  reason,  he  should,  when  his  ship  is  filled,  still 
crowd    in  more  than  the  vessel   can  carry,  or  the   market 
will  justify. 

145.  This  would  be  foolish  indeed,  but  not  more  so  than 
for  a  man  to  select  and  measure  his  food  without  regard  to 
the  wants  of  nutrition  in  his  body,  or  to  the   power  of  the 
digestive  organs  to  convert  it  into  the  material  of  the  blood, 
but  according  to  the  pleasure  of  its  passage  from  the  table  to 
the  stomach.     In  the  case  of  the  ship,  when  the  unfitting  or 
excessive  cargo  is  crowded  into  the  hold,  it  can  be  taken  out, 
and  the  vessel  spared  the  danger   of  sinking,   and  the  mer- 
chant saved  the  loss  on  merchandise  sent  to  a  wrong  desti- 
nation, and  no  damage  need  be  sustained  but  the  labor  of 
loading  and  unloading.     But,  when  the  food  is  once  in  the 


70  PHYSIOLOGY    AND    HEALTH. 

stomach,  there  is,  generally,  no  return ;  whatever  is  once 
there,  although  out  of  place,  must  remain,  or  go  onward  at 
the  cost  of  comfort  and  strength  of  this  organ,  and  of  the 
whole  body. 

146.  It  would  seem  that  these  principles  must  be  plain  to 
every  one,  so  that  no  man  would  overload  or  improperly  load 
his  stomach,  any  more  than  he  would  his  ship  or  his  wagon, 
for  so  slight  a  motive  as  the  pleasure  of  the  first  step  in  the 
work.     Yet  this  error  is  among  the  most  common  in  society. 
It  seems  to  be  forgotten  that  the  appetite  and  the  mouth  are 
made  to  subserve  digestion  and  nutrition  ;  and  the  world  eats 
as  if  the  whole  digestive  system  were  the  mere  servant  of  the 
palate,  and  made  to  carry  whatever  burden  this  may  impose 
upon  it. 

147.  The  pleasures  of  good  eating  occupy  many  men's 
thoughts ;  they  are  the  subject,  of  much  conversation ;  they 
have  had  their  praises  sung  by  many  a  poet;  while  the  fitness 
of  food  for  the  purposes  of  life  is  scarcely  thought  of,  and  still 
more  {infrequently  discussed.     Few  there    are  who   do  not 
understand  the  flavor  of  the  various  articles  of  diet,  or  the 
pleasantness   or  unpleasantness  of  the  different  methods  of 
cookery.     Yet  the  nutritive  power,  or  digestibility  of  these 
articles,  and  the  effects  of  cookery  upon  their  qualities,  are 
almost  unknown  to  the  world. 

148.  With  this  ignorance  of  the  true  purposes  and  conse- 
quences  of  eating,  and  with  the  too  common  disregard  of 
the  wants  of  the  body  and  the  powers  of  the  stomach,  it  is 
not  surprising   that    appetite  should  very  frequently  be  the 
governing   law  in  this  matter,  and  that  men  should  eat  for 
pleasure,  rather  than  for  nourishment  and  strength ;  and  such 
is  the  fact.     The  stomach  is  made  the  receptacle  of  what- 
ever  the    capricious    and    ungoverned    appetite    selects  and 
sends  to  it.     Our  tables  are  spread,  not  only  with  substan- 
tials  that  nourish  the  body,   but  with  delicacies   that  tempt 
the  palate.     We  eat  not  only  enough  to  support  the  body,  but 
often  we  add  to  this  much  more  for  the  mere  enjoyment  of 
the  act,  and  we  urge   our   friends  to  partake  of  the  various 


DIGESTION    AND    FOOD.  71 

kinds,  not  because  the  food  is  nutritive,  —  not  because  they 
are  hungry  and  need  it,  —  but  on  account  of  the  inviting  flavor 
of  the  dishes.  Our  argument  to  our  guests  is  not,  "  You  are 
hungry,  and  this  will  strengthen  you,"  but,  "  This  is  pleas- 
ant to  the  appetite,  and  you  will  for  a  moment  enjoy  it." 

149.  The  appetite  is  made  the  means,  and  the  stomach  is 
compelled  to  bear  the  burden,  of  much  of  our  enjoyments, 
and  of  our  hospitality.     Men  manifest    their  love    for  their 
friends  by  offering  them  delicious  food,  by  inviting,  and  even 
urging,  them  to  partake  of  what  their  systems  do  not  need, 
and  their  powers  of  digestion  cannot  easily  bear.     And,  in 
this  earnest    and    well-intentioned  endeavor   to  make    their 
hearts  glad,  they  give  their  stomachs  pain  and  disease.     There 
is  a  great  proneness  among  mankind  to  make  many  occasions 
of  public  and  private    festivity.     There  is  a  strong  inclina- 
tion, when  men  gather  together  for  enjoyment,    in  whatever 
way, —  whether  for  dancing,  or  conversation,  or  for  the  cele- 
bration of  a  public  and  joyful   event,  —  to  add  to  the  social 
pleasure  the  luxuries  of  good  and  plentiful  eating.     And  the 
very  means  they  use  to  signify  their  present  joy,  is  the  source 
of  future  suffering  in  a  greater  or  less  degree,  in  proportion  to 
their  disobedience  of  the  law  of  nutrition. 

150.  With    children,  the  wants  of  nutrition  appear  first, 
before  all  other  wants ;  the  appetite  for   food    predominates- 
over  other  desires,  and  is  ever  seeking  for  gratification.     This 
seems  to  be  the  readiest  means  of  pleasing  them ;  it  is  there- 
fore frequently  appealed  to  by  those  who  wish  to  give  them 
pleasure.     Delicacies  of  many  sorts  —  fruits,  cakes,  confec- 
tionery—  are  offered  them  by  those  kind-hearted  but  indis- 
creet friends,  and  too  often  by  their  parents  and,  nurses,  as  a 
means  of  soothing  pain  or  assuaging  grief,  or  even  pacifying 
anger,  or  winning  approbation. 

151.  Men  and  women  of  every  age,  as  well   as  children, 
generally  consider   it  a  proper  and  harmless  privilege  to  in- 
dulge this  appetite  when  delicacies  invite,  and  when  oppor- 
tunities offer.     Some  few  of  them  are  epicures,   and,  finding 
daily  opportunities,  always  eat  to  oppressive   fulness.     But 


«  PHYSIOLOGY    AND    HEALTH. 

most  of  them  are  generally  more  moderate  in  their  indul- 
gence, yet  overstep  now  and  then,  by  adding  to  the  sufficien- 
cy of  their  regular  meals  another  and  another  portion  which 
tempts  their  taste,  or  by  taking  at  other  times  some  pleasant 
little  refreshment,  which  chance  may  throw  in  their  way,  but 
which  afterwards  becomes  a  source  of  oppression  to  their 
organs  of  digestion.  There  are  others  whose  habits  of  eat- 
ing are  generally  in  accordance  with  the  natural  law,  and 
whose  daily  food  is  usually  no  more  and  no  other  than  their 
nourishment  requires.  Yet  these  will,  on  perhaps  rare  occa- 
sions, meet  in  parties,  or  go  upon  excursions  of  pleasure, 
which  include  a  feast;  and  then  they  give  free  rein  to  their 
appetites,  and  induige  in  the  pleasures  of  the  table. 

152.  All  these  indulgences  of  appetite,  when  for  nutrition 
there  is  no  call  for  food,  or  when  we  have  already  eaten  as 
much  as  we  can  with  ease  convert  into  chyme,  must  neces- 
sarily lay  a  tax  upon  the  stomach ;  and,  so  far  as  they  exceed 
the  wants  of  the  body,  they  do  not  add  to  its  strength,  but, 
on  the  contrary,  they  bring  upon  it  weakness.  These  are 
plainly  violations  of  the  'law  of  life,  and  are  inevitably  fol- 
lowed .  by  the  consequences  of  disobedience.  The  conse- 
quences are  not  one  and  the  same  for  all,  whatever  may  be  the 
error,  but  they  are  measured  out  in  precise  proportion  to  the 
delinquency.  The  constant  epicure  suffers  more  than  the 
occasional  gourmand,  and  the  frequent  gourmand  more  than 
he  who  but  rarely  indulges  in  eating  more  than  he  needs. 
But  none  escape.  All  —  the  least  as  well  as  the  greatest 
offenders  —  have  greater  or  less  oppression.  In  some  it  is 
almost  imperceptible ;  and  in  others  it  is  almost  intolerable 
It  is  a  singular  perversion  of  the  digestive  organs,  to  compel 
them  to  receive  and  to  attempt  to  digest  food  of  such  quan- 
tities as  are  not  needed  for  nutrition,  and  of  such  qualities 
as  nature  never  intended  they  should  convert  into  chyle  for 
the  blood.  But  this  apparatus  is  sometimes  perverted  to 
stranger  and  more  dangerous  purposes  than  even  these. 
Children  and  men  put  into  their  mouths,  and  masticate,  and 
often  swallow,  some  materials  which  cannot  be  dissolved  in 


DIGESTION  AND    FOOD.  73 

the  stomach,  and  from  which  no  nutriment  can  be  extracted. 
From  diseased  appetite  or  perverse  habits,  some  boys  and 
girls  chew  India-rubber,  pitch,  or  slate-pencils.  I  once  found 
almost  an  entire  school  in  the  habit  of  chewing  one  or 
another  of  these  things.  These  unnatural  things  disturb  and 
disorder  the  stomach,  and  often  result  in  very  serious  disease. 
Some  of  the  most  inveterate  and  distressing  cases  of  indiges- 
tion arose  from  such  beginnings  as  these. 

153.  Although  we  are  not  allowed  to  exceed  the  wants  of 
the  system  or  the  digestive  power,  in  the  least  degree,  with- 
out suffering,  yet  the  opposite  error  is  equally  contrary  to 
the  law  of  life.  Nature  is  very  exact  in  her  demands,  as 
well  as  in  her  concessions.  She  will  not  give  health  and 
strength  for  one  morsel  more  than  her  requirements;  nor 
will  she  relax  and  give  unalloyed  comfort  and*  full  vigor  for 
one  morsel  less.  A  definite  quantity  of  nutriment,  varied 
to  suit  the  varieties  of  persons,  will  nourish  and  strengthen, 
and  entirely  meet  the  wants  of  each  individual.  Any  smaller 
quantity  will  give  less  strength  and  power  of  labor  of  body 
and  of  mind.  The  strength  of  the  laborer  will  fall  short  of 
its  fulness,  in  proportion  to  the  diminution  of  his  nourish- 
ment. Whether  this  diminution  be  in  the  quantity  or  the 
quality  of  his  food,  the  result  of  weakness  is  the  same. 
Whether  it  be  from  a  short  allowance  of  good  food,  or  the 
innutritious  quality  or  the  indigestible  nature  of  bad  food, — 
which  cannot  be  converted  into  chyme  or  chyle,  —  or  from 
whatever  cause,  less  than  the  ordinary  and  sufficient  quan- 
tity of  nutriment  is  sent  from  the  digestive  organs  to  the 
blood-vessels,  the  final  end  is  that  the  frame  is  not  fully  nour- 
ished or  strengthened.  Poor  meats,  thin  soups,  and  innu- 
tritious roots,  are  insufficient  for  the  laboring  man ;  and  it  is 
bad  economy  to  endeavor  to  support  him  on  such  diet. 

154.  Even  students,  and  men  engaged  in  sedentary  employ- 
merits,  cannot  maintain  their  full  health,  and  their  energy  and 
clearness  of  brain,  upon  a  diet  lower  than  their  natural  re- 
quirements. Some  students  in  college,  for  the  sake  of  econ- 
omy, endeavor  to  live  upon  very  little  and  cheap  food.  Bui 
7 


74  PHYSIOLOGY    AND    HEALTH. 

they  suffer  in  consequence,  and  are  unable  to  pursue  their 
studies  with  their  original  vigor.  A  freshman  in  college 
endeavored  to  support  his  body  with  eight  ounces  of  bread 
a  day,  without  other  vegetable  food  or  meat.  He  followed 
this  plan  four  weeks,  and  in  that  time  suffered  from  head- 
ache, nervousness,  general  debility,  and  indisposition  to  ap- 
ply his  mind  to  his  books.  But  on  returning  to  the  usual 
but  moderate  diet  of  other  students,  he  regained  his  usual 
health  and  mental  vigor. 


CHAPTER   XVI. 

Greater  Flow  of  Blood  and  of  nervous  Energy  to  Parts  and  Organs 
in  Motion,  and  to  Stomach  during  Digestion.  —  Action  in  other 
Parts  interferes  with  Digestion.  —  Mental  Labor  has  the  same  Ef- 
fect.—  Rest  requisite  after  Eating,  and  before  Eating.  —  Gymnas- 
tic Exercises  at  Cambridge. 

155.  WHEN  any  one  organ  or  portion  of  the  body  is  in 
action,  more  blood  is  sent  to  it,  through  the  arteries,  to  meet 
the  changes,  and  supply  its  waste,  and  support  its  powers  ; 
at  the  same  time,  there  is  more  nervous  energy  sent  to  this 
part,  to  quicken   its  activity.     When  this  unusual   flow  of 
blood  and  nervous  influence  is  toward  one  spot,  there  must 
be  proportionably  less  sent  to  all  the  other  parts,  and  conse- 
quently the  rest  of  the  body  must  be  comparatively  languid 
or  inactive.     No  two  portions  or  organs  can,  then,  be  kept 
in  the  fullest  and  most  vigorous  action  at  the  same  time,  for  the 
extraordinary   flow   of    blood,  arid   of    quickening   nervous 
power,  cannot  be  supplied  to  both  or  all  at  once. 

156.  This  is  particularly  applicable  to  digestion  of  food 
in  the  stomach.     While  this  is  going  on,  the  preponderance 
of  blood  is  towards  this  organ,  to  sustain  this  new  action, 
and  furnish  the  materials  of  the  gastric  juice  ;  consequently, 
there   must   be   a  smaller  proportion   of  blood  in  the  other 
parts  of  the  body.     Upon  the  same  principle,  the  nervous 


DIGESTION     AND    FOOD.  75 

influence  flows  in  a  larger  proportion  to  the  stomach,  —  the 
seat  of  action,  —  and  in  a  less  proportion  to  the  rest  of  the 
frame.  It  is  plain,  therefore,  that  while  digestion  is  going 
on,  or  until  the  gastric  juice  is  prepared  sufficiently  for  the 
digestion,  the  other  parts  have  a  smaller  supply  of  blood  to 
sustain  their  actions,  and  less  nervous  power  to  quicken 
their  life;  they  must,  consequently,  be  comparatively  lan- 
guid, and  should  be  suffered  to  rest. 

157.  Full,  vigorous  action  cannot,  then,  be  well  sustained 
in  two  parts  of  the  body  at  the  same  time.     If  this  be  at- 
tempted, one  or  the  other  must  fail,  or  both  be  imperfect. 
In  order  to  insure  perfect    digestion,  the  stomach  must  be 
allowed  to  do  its  perfect  work,   and  no  other  organ   must 
make  active  exertions  while  this  is  going  on.     We  should, 
therefore,  let  both  the  body  and  the  mind  rest  for  a  short 
period  after  each  meal.     It  is  a  custom  in  Spain  to  take  a 
short  nap  after  dinner.     This  is  often  quoted  as  a  proof  of 
Spanish  indolence.     It  is  no  indication  of  indolence.     It  is 
rather  a  mark  of  wisdom  ;  for  this  leaves  the  digestive  organs 
an  opportunity  to  do  their  work  undisturbed,  and  to  prepare 
for  the  body  that  new  nutriment  which  is  to  give  it  power 
of  action  afterwards. 

158.  Action  of  the  mind,  as  well  as  action  of  the  body, 
interferes  with  digestion;  and  the  digestive  process  inter- 
feres with  mental  activity.     Immediately  after  a  hearty  din- 
ner, one  is  indisposed  to  think,  or  thinks  but  lightly.     He  is 
averse  to  study,  to  business  cares,  to  calculations,  and  to  any 
matter  that  requires  vigorous  thought.     Ask   him   then   to 
consider  a  grave  subject,  or  ask  a  boy,  in  a  similar  situation, 
to  learn  a  difficult  lesson,  and  either  will  be  glad  to  postpone 
the  labor  until  the  digestive  process  is  over.     If  severe  men- 
tal labor   be  undertaken,   it  will  not  be  carried  on  easily  ; 
and,  if  it  be  carried  on  at  all,  it  will  be  at  the  cost  of  the 
digestion.     Both  these  operations  cannot  be  performed  suc- 
cessfully at  the  same  time.     Yet  it  is  not  necessary  that  the 
brain   be  perfectly  dormant.     A  pleasant   and  light  action, 
such  as  accompanies  cheerful  conversation,  or  reading  light 
works,  does  not  interfere  with  this  work  of  the  stomach. 


76  PHYSIOLOGY   AND   HEALTH. 

159.  If  any  other  organ  or  system  be  put  in  violent  exer- 
cise, or  in  a  state  of  high  excitement,  immediately  or  soon 
after    the    meal    is    eaten,  the  digestion    is    interrupted,   or 
even  suspended.     A  striking  experiment  was  tried  by  a  gen- 
tleman in   England.     He  gave  to  several  hounds  as  much 
food  as  they  could  eat,  and  then  put  some  of  them  into  a 
kennel  where  they  had  no  opportunity  of  motion ;  the  others 
were  put  upon  the  chase,  and  kept  running  in  hot  pursuit  of 
game  for  an  hour  or  more.     At  the  end  of  this  period,  he 
killed  some  of  both  classes,  and  examined   their  stomachs. 
He  found  the  food  in  the  stomachs  of  those  dogs,  which  had 
been  running,  in  the  same  condition  as  when  first  swallowed  ; 

—  it  had  remained  unchanged.  But  in  the  stomachs  of  the 
others,  which  had  been  at  rest,  it  was  digested  and  converted 
into  pulpy  chyme,  and  had  gone  mostly  out  of  the  stomach 
into  the  alimentary  canal. 

160.  It  may  not  be  necessary  that  we  should  sleep,  like 
the  Spaniard,  after  our  dinner,  but  it  is  necessary,  for  per- 
fect digestion  of  the  food,  and  effectual  nutrition  of  the  body, 
that  we  do  not,  like  the  running  hounds,  engage  in  violent 
exercise  at  that  time.     Indeed,  all  active  labor  immediately 
after  eating,  interferes  with  digestion,  and  of  course  with  the 
purposes  of  the  meal ;  and  this  interruption  must  be  in  pro- 
portion  to  the  activity  of  the  motion.     If  violent  exercise 
suspends  entirely  the   work   of  the    stomach,    exercise   less 
laborious  will  interfere  with  it  in  some  degree.     Yet  abso- 
lute rest  or  sleep   is  not   necessary.     Dr.  Beaumont   says, 
"Gentle  exercise  facilitates  the  digestion  of  food."     In  the 
course  of  an  hour  from  the  meal,  the  gastric  juice  is  sent  into 
the  stomach,  sufficient  for  the  digestion,  and  is  completely 
mixed  with  the  food.     Then  we  may  proceed  to  active  em- 
ployment, without  fear  of  disturbing  the  digestive  process. 

161.  When  any  of  the  organs  or  limbs  have  been  greatly 
exercised,  there    come    a    fatigue    in    that   part  which  has 
labored,  and  a  lassitude  in  the  whole  frame;    and  then  none 
of  our  powers  are  disposed  to  active  exertion;  all  want  rest. 
When  the  fireman's  feet  are  fatigued  with  running  a  long 


DIGESTION    AND    FOOD.  77 

distance  to  a  fire,  he  is  not  ready  to  take  hold  of  the  brakes 
of  the  engine  and  pump  with  successful  vigor.  Nor,  after 
fatiguing  the  arms  with  the  engine,  is  he  inclined  to  make 
equal  exertion  with  the  feet  in  running  a  race  homeward. 
102.  Fatigue  of  the  body  affects  the  mental  powers  in 
the  same  way.  When  the  laborer  has  finished  a  very  hard 
day's  work,  or  when  the  fireman  returns  from  his  violent 
exertions  at  afire,  he  is  disinclined  to  active  thought,  and, 
perhaps,  even  to  read,  and  may  fall  asleep  over  his  book. 
Nor  at  any  time  do  we  readily  think  upon  any  serious  sub- 
ject, or  attend  to  any  business  that  requires  grave  thought, 
immediately  after  we  have  made  great  and  fatiguing  exertion. 

163.  While  any  limb  or   organ  is  in  action,  there  is  a 
greater  waste    of  particles.     At  the  same  time,  there  is  a 
greater  flow  of  blood  to  supply  this  waste,  and  of  nervous 
power  to  quicken  the  action.     But,  if  the  action  be  violent, 
the  waste  is  greater  than  the  new  supply,  and  consequently 
the   part  is  exhausted,  and    the    body  feels  fatigued.     The 
exhaustion   of  particles   and   the   fatigue   remain    after  the 
action   is  over.     If  we  are  then  quiet,  the  blood  and  the 
nervous  energy  still  continue  to  flow  in  unusual  quantity,  to 
restore  the  previous  waste,  and  to  revive  the  diminished  life. 
By  this  means,  we  rest,  and  recover  lost  powers.     While  the 
brain  and  the  blood-vessels  are  thus  restoring  any  fatigued 
part,  they  cannot  sustain  a  vigorous  action  in  another ;  and 
if  we  then  attempt  to  exercise  the  muscles,  or  stomach,  or 
brain,  and  work,  digest,  or  think,  we  shall  do  it  but  languid- 
ly,—  probably  unsuccessfully,  —  because  the  blood  and  ner- 
vous energy  which  are  needed  to  sustain  these  actions  are 
wanted  and  used  elsewhere. 

164.  During  the  first  process  of  digestion,  the  stomach 
requires  a  greater  flow  of  blood  and  of  nervous  energy  to 
sustain    this    action.     But   if  these  be  still  required  in  re- 
storing the  waste,  and  the  power  of  other  parts,  exhausted 
and  fatigued  by  previous  exertion,  they  cannot  be  given  to 
the   stomach.     If,    therefore,  when  we    are   much    fatigued 
with    exertion  of  the  muscles  or  of  the  brain,  we  fill  our 

7* 


78  PHYSIOLOGY    AND    HEALTH. 

stomachs  with  food,  this  organ  cannot  receive  from  the 
blood,  or  from  the  nervous  system,  that  aid  which  is  neces- 
sary to  enable  it  to  digest.  The  laborer,  therefore,  should 
not  go  directly  from  his  hard  work,  nor  the  student  from  his 
severe  study,  nor  the  merchant  from  his  oppressive  anxieties, 
to  the  table.  But  each  should  allow  a  short  interval  of  rest, 
and  then  he  is  prepared  to  eat  and  digest  his  food. 

165.  It  is  not  uncommon  for  students  to  devote  the  hour 
before  dinner  to  their  exercise.  Schools  and  academies,  and 
even  colleges,  usually  have  this  hour  of  leisure  to  be  taken 
from  books  and  devoted  to  recreation.  That  there  should  be 
rest  of  the  brain  at  this  time  is  well.  When  the  gymnasium 
was  established  at  Harvard  University,  in  1826,  the  students 
were  invited  to  go  to  the  playground  at  twelve,  and  engage 
in  the  gymnastic  exercises  till  one  o'clock.  These  were 
very  active,  and  some  of  them  violent,  for  men  and  boys  of 
their  strength,  so  that,  when  they  left  the  field  for  dinner, 
they  were  generally  fatigued,  and  some  were  almost  ex- 
hausted. Those  who  were  most  fatigued,  ate  their  dinner 
with  less  than  their  usual  relish,  and  felt  neither  refreshed 
nor  comfortable  afterward.  Their  stomachs  could  not  digest 
the  meal  with  the  usual  ease,  and  consequently  they  were 
heavy,  and  indisposed  for  study  in  the  afternoon. 


CHAPTER  XVII. 

Cheerful  Conversation  at  Meals  aids  Digestion.  —  Silent  and  solitary 
Meals  unfavorable  to  Digestion.  —  Consequences  of  Abuse  of  di- 
gestive Organs. 

166.  DURING  the  time  of  eating,  the  body  should  be  seated 
in  a  comfortable  and  easy  position,  and  all  the  organs  and 
powers,  except  the  digestive,  should  be  at  rest.  The 
muscles  and  the  brain  should  be  quiescent.  The  mental 
and  the  moral  powers  should  yield,  for  the  time,  to  the  busi- 
ness of  calm  nutrition.  The  mind  should  therefore  be  free 
from  the  burden  of  deep  reflection,  care,  and  anxiety.  None 


DIGESTION    AND    FOOD.  79 

of  the  evil  passions  —  anger  and  envy  —  should  ever  be  al- 
lowed to  come  to  the  table.  All  great  and  severe  thought,  all 
labored  discussions,  and  matters  of  business,  should  be  ban- 
ished thence,  and  light  and  cheerful  conversation  take  their 
places.  The  lively  play  of  the  social  affections,  the  pleasant 
intercourse  of  family  and  friends,  the  enlivening  flow  of  wit 
and  humor,  keep  the  brain  in  action,  but  not  in  labor 
With  these,  the  blood  moves  more  freely,  and  the  nervous 
energies  flow  more  joyously,  and  the  work  of  digestion  is 
moie  readily  begun,  and  more  easily  carried  on,  and  they 
should  ever  be  present  at  our  meals. 

167.  The  eating  hour  is  the  time  to  cultivate  the  social 
nature.  This  harmonizes  well  with  the  lively  flow  of  spirits 
that  aids  the  digestive  process.  It  is  better,  therefore,  not  to 
eat  alone,  nor  even  in  silence.  The  solemn  stillness  that 
reigns  over  the  table  of  some  families,  the  unbroken  quiet- 
ness which  a  stern  but  mistaken  discipline  imposes  upon  some 
children,  are  at  variance  with  the  best  interests  of  the  time. 
They  lay  a  weight  upon  the  brain,  a  burden  upon  the  spirit, 
and  prevent  that  quickening  which  social  cheerfulness  would 
give  to  the  stomach. 

158.  These  several  steps  and  conditions  of  digestion,  of 
nutrition,  and  strengthening,  were  established  by  the  Creator. 
They  are  among  the  very  laws  of  our  being,  and  cannot  be 
changed.  The  only  way  we  can  gain  the  most  strength  for 
labor  of  any  sort,  is  by  perfect  obedience  to  these  laws,  and 
fulfilment  of  these  conditions.  All  failure  of  this  must  result 
in  loss,  and  defeat  the  very  purpose  for  which  they  are  vio- 
lated. The  loss  is  immediate  in  the  depreciation  of  power, 
greater  or  less,  in  proportion  to  the  delinquency.  The  loss 
is  also  accumulative  and  remote,  because  the  stomach  itself 
loses  power  to  do  its  ordinary  duty  when  unnatural  burdens 
are  imposed  upon  it,  or  when  it  is  not  allowed  the  requisite 
aid  to  bear  them. 

169.  The  first  consequence  of  neglect  of  these  laws  of 
eating  is,  an  imperfect  nutrition,  a  comparative  weakness  at 
the  time,  inability  to  accomplish,  with  the  brain  or  the 


80  PHYSIOLOGY   AND   HEALTH. 

muscles,  what  otherwise  could  have  been  done ;  therefore,  a 
direct  loss  of  power,  and  of  means  of  production.  But  the 
later  consequence  is  more  important  and  lasting.  The 
stomach  being  called  upon  to  digest  unmasticated  food,  or 
more  than  it  can  dissolve,  is  disturbed  and  wearied  with  the 
excess  of  labor,  and  falters.  It  struggles,  but  struggles  in 
vain,  until  it  exhausts  much  of  its  power  in  the  wearisome 
effort.  It  then  becomes  so  weak  that  it  cannot  digest  even 
the  common  food,  which  in  good  health  it  would  have  easily 
done,  and  becomes  so  irritable  as  to  bear  only  in  pain  the 
natural  and  proper  burden.  This  is  dyspepsia,  which  is  the 
common  result  of  improper  use  of  our  organs  of  digestion. 
This  is  a  disease  painful  to  be  borne,  and  difficult  to  be 
relieved,  and  often  ends  only  with  life.  In  its  first  stage, 
the  work  of  digestion  is  imperfect ;  and  in  the  second,  the 
digestive  machine  is  impaired,  and  finally  destroyed. 


CHAPTER  XVIII. 

Animal  and  Vegetable  Food.  —  Northern  Nations  carnivorous.— 
Equatorial  Nations  herbivorous.  —  Vegetable  Diet.  —  Mixed  Diet 
—  Stimulating  Food.  —  Climate  and  Season  affect  Diet.  —  Vegeta- 
ble Diet  in  Torrid  Zone.  —  Mixed  Diet  in  Temperate  Zone. 

170.  THERE  is  a  great  variety  of  food.     There  are  many 
kinds  that  differ  widely  from  each  other ;   and  these  may  be 
prepared,  compounded,   and   cooked    in   a  great   variety  of 
ways  ;   so  that  the  differences  caused   by  art  may  be  even 
more  and  greater  than  the  differences  of  nature.     It  is  im 
portant  for  us  to  know  which  of  these  afford  us  the  easiest 
and  the  best  nutrition. 

171.  The  first  natural  division  of  food  is  into  that   of 
vegetable  and  animal  origin.     It  is  not  yet  a  settled  question, 
which  of  these  is  best 'fitted  for  the  nutrition  of  the  human 
body,  —  which  will  give  to  man  the  greatest  strength  and 
power  of  action,  —  the  greatest  comfort  and  most  perfect 


DIGESTION    AND    FOOD.  81 

health,  —  the  clearest  brain  and  the  longest  duration  of  life. 
Some  have  contended,  that  man  was  intended  to  eat  only 
of  the  fruits  and  vegetables  of  the  earth;  while  others  main- 
tain, with  equal  confidence,  that  he  should  add  to  these  the 
flesh  of  beasts.  But  none  have  thought  that  he  should  live 
exclusively  upon  animal  food. 

172.  The  advocates  of  both  these  doctrines  find  exten- 
sive examples  in  the  various  nations  and  the  various  individ- 
uals of  mankind.     Many  nations  within  the  tropics  live  upon 
vegetable  food  alone;    while  some  tribes  within  the  arctic 
circles  feed    almost   entirely   upon  the    flesh  of  animals  or 
fish.     The    inhabitants    of  the    cold   regions   of  the    earth 
are  generally  carnivorous,   and  the  residents  of  the  warm 
countries  herbivorous;  while  those  who  live  in  the  temperate 
climates  are  both  carnivorous  and  herbivorous.  *  Here  in  the 
United  States,  and  in  the  central   regions  of  Europe,   the 
mixed  diet  is  almost  universal;  and  the  people  are  as  healthy, 
and  have  as  great  a  duration  of  life,  as  any  upon  earth. 

173.  There  are  many  individuals,  in  this  and   in  other 
countries,  who  confine  themselves  to  vegetable  diet.     They 
believe    they    enjoy    better    health,    and    maintain    greater 
strength  of  body  and  mind,  than  those  who  live  upon  mixed 
diet.     The  experiment  has  not  been  tried  on  a  sufficiently 
extensive  range  to  determine  its  value.     It  has  not  proved, 
a  failure,  nor  has  it  demonstrated,  to  the  satisfaction  of  all, 
that  flesh  is    injurious.     There  are  no  advocates    here    for 
the  exclusively  flesh  diet;  but  the  doubt  is  only  between  the 
mixed  on  the  one  side,  and  the  vegetable  food  on  the  other. 

174.  It  is  generally  believed,  among  civilized  nations,  that 
the  mixed  diet  is  the  best  for  man  —  that  this  will  give  him 
the  fullest  health  and  the  longest  life.     The  organization  of 
the  human  body  admits  this.     The  form  and  arrangement  of 
the  teeth  (§  10,  p.  12)  allow  him   to  cut  and  masticate  both 
the  animal  and  the  vegetable  food ;  and  the  structure  of  the 
stomach  and    intestinal  canal  enables  man  to  digest  both ; 
so  that  he  can  use  either  exclusively,  as  the  Esquimaux  eat 
flesh,  and  the  Hindoos  eat  rice ;  'or  he  can  use  both,  as  most 


82  PHYSIOLOGY  AND    HEALTH. 

of  the  inhabitants  of  the  temperate  climates  eat  bread  and 
meat  together.  Admitting,  then,  this  question  to  rest  for 
the  present,  and  that  we  are  to  use  the  mixed  diet  as  we 
have  done,  still,  there  are  other  and  subordinate  questions, 
with  regard  to  each  individual,  to  be  answered,  before  we 
can  determine  what  we  shall  eat. 

175.  The  various  kinds  of  food  differ  as  to  their  effect 
upon  the  animal  body.     One  kind,  including  most  meats,  is 
stimulating,    and    gives    a   greater    elasticity   of  life.     This 
would  excite  some  fever,  when  there  is  a  feverish  tendency. 
Another    kind,  including    fish,  eggs,  vegetables,  grain,  and 
fruits,  has  no  stimulating  power.     These  would  not  quicken 
the  pulse  nor  excite  fever.     The  spices,  and  food  in  which 
they  are  mixed,  are  warm  and  heating.     Many  of  the  vegeta- 
bles are  cooling.     These  differences  must  be  known,  before 
the  fitness  of  the  various  kinds  to  the  condition  of  man  can 
be  determined. 

176.  Climate  and  season  affect  the  human  body,  and  its 
wants  and  power  of  digestion,  very  materially.     We  want  a 
somewhat  different  diet  in  the  warm  and  in  the  cold  seasons. 
We  eat  more  meat  and  stimulating  food  in  the  winter,  and 
more  vegetable  and  cooling  food  in  the  summer.     The  tribes 
about  the   arctic  circle  live  almost   exclusively  upon  animal 
food.     They  will  eat  meat  in  great  quantities  without  either 
bread   or  vegetables   to    accompany   it.      They    devour  fish 
of  the  coarsest  kinds,  —  whale,  porpoises,  &/c.,  —  such  as  we 
think  unfit  for  our  nutrition,  and  impossible  to  be  digested 
in  our  stomachs.     They  will  drink  whale  oil  with  as  much 
apparent  relish   as  we  drink  milk  or  water.     The  voyagers 
to  these  northern  regions,  while  they  are  passing  the  winter 
among  these  people,  fall  into  their  habits  of  eating :  they  find 
both  that  they  need,  and  that  their  stomachs  can  digest,  this 
coarse  and  stimulating  food,  which  would  have  been  oppres- 
sive and  indigestible  at  home  in  a  temperate  climate. 

177.  On  the  contrary,  the  inhabitants  of  the  tropical  re- 
gions live  very  much,  and  some  nations  entirely,  upon  vege- 
table food.     Some  of  these  nations  never  eat  meat,  and  most 


DIGESTION    AND    FOOD.  83 

of  them  eat  it  rarely ;  certainly,  they  make  it  a  secondary 
article  of  their  diet.  But  in  the  temperate  climates,  in  the 
middle  regions  between  the  extremely  hot  and  the  extremely 
cold,  a  mixed  diet  is  generally,  and  almost  universally,  adopted. 
Even  here,  the  proportions  of  the  meat  and  the  vegetable 
vary  with  the  climate.  In  the  warmer  countries,  —  in  the 
south  of  Europe,  and  as  we  approach  the  tropics,  —  the  vege- 
table predominates;  and  among  the  northern  nations,  to- 
ward the  frigid  zone,  the  meat  is  the  main  dependence  for 
nourishment.  This  is  in  obedience  to  the  general  law  of 
life,  that  the  body  needs,  and  the  stomach  can  bear,  a  more 
highly  stimulating  food,  when  and  where  the  atmosphere  is 
cold,  than  when  and  where  it  is  warm. 


CHAPTER  XIX. 

Temperaments.  —  Lymphatic.  —  Nervous.  —  Sanguine.  —  Bilious. 
—  Difference  of  the  Excitable  and  the  Inexcitable. —  Diet  to  be 
regulated  according  to  Temperament. 

178.  There  are  differences  of  individuals  that  should  re- 
quire corresponding  differences  of  diet.  It  is  plain,  even  to 
the  most  careless  observer,  that  men  are  not  all  alike.  Orie 
is  dull,  difficult  to  be  moved,  and  habitually  inactive.  Anoth- 
er is  quick,  irritable,  and  easily  excited  or  depressed  ;  he  is 
gratified  or  disturbed  with  very  small  matters  and  is  restless 
in  his  disposition  and  habits.  These  differences  arise  from 
the  physical  condition  of  the  individuals,  from  their  ori- 
ginal organization,  and  constitute,  in  part,  what  are  called  the 
various  temperaments  of  men.  Physiologists  have  divided 
mankind  into  several  classes,  as  to  temperaments,  according 
to  the  predominant  traits  in  their  constitution.  Some  have 
made  four  of  these  classes,  calling  them  the  lymphatic,  ner^ 
vous,  sanguine,  and  bilious  temperaments.  Others  have 
made  more  classes.  But  however  few  or  many  any  physiolo- 


84  PHYSIOLOGY    AND    HEALTH. 

gist  has  adopted,  there  have  been  combinations  and  mixtures 
of  traits,  forming  other  and  intermediate  classes,  such  as  the 
nervous-bilious,  the  nervous-sanguine,  &c. 

179.  In  persons  of  lymphatic  temperament,   the  form  is 
generally    full    and    round,  fat,  or  tending  to  fatness;    the 
skin  is  soft  and  rather  full ;  and  the  flesh  is  loose,  and  some- 
what flabby ;  the  muscles  are  weak,  and  the  whole  body  is 
inactive.     There  is  an    indisposition  to  exertion,  either  of 
body    or    of  mind ;    the   temper    is   calm    and    inexcitable, 
and  the  passions  are  not  easily  roused.     Men  of  this  temper- 
ament are  not  easily  excited,  and  can  bear  much  stimulation. 
They  should  therefore  have  food  of  a  stimulating  nature,  — 
such  as  beef,  mutton,  coffee,  —  which  tend  to  counteract  their 
indolent  disposition.     On  the   contrary,  their  natural   indo- 
lence is  increased  by  a  weak  and  unstimulating  diet.     Fish, 
oysters,  eggs,  and  most  of  the  vegetable  roots,  would  aggra- 
vate the  peculiarities  of  this  temperament. 

180.  The  nervous  temperament  is  marked    by  predomi- 
nance of  the  brain  and  nerves,  and  by  great  nervous  excita- 
bility.    Men  of  this  class,  are  easily  excited,  and   as  easily 
depressed.     They    are   susceptible   of   high     pleasures    and 
great  distress.     They  are  very  sensitive  to  external  influence, 
both  upon  their  body  and  upon  their  mind.     A  strong  stimu- 
lating diet  would  increase  these  peculiarities ;  but,  to  coun- 
teract  them,   a  mild   and  cooling,  yet  a  nutritious  diet  is 
necessary. 

181.,  In  the  sanguine  temperament,  there  is  greater  devel- 
opment and  activity  of  the  apparatus  for  the  circulation  of 
the  blood,  and  nutrition  of  the  heart  and  blood-vessels.  All 
the  physical  powers  are  strong,  elastic,  and  easily  excited. 
Men  of  this  class  are  bold  and  resolute;  they  are  ready  to 
act,  but  not  persevering ;  they  soon  become  weary,  especially 
if  difficulties  present  themselves.  Their  bodily  faculties 
predominate  over  their  mental,  and  they  are  men  of  action 
rather  than  of  thought.  They  are  not  scholars,  nor  the  most 
cautious  men  of  business.  The  boys  are  foremost  at  play, 
but.  not  in  school.  These  cannot  bear  excitements  or  stimu- 
8* 


DIGESTION    AND    FOOD.  85 

lants,  without  danger  of  disease.  Stimulating  food  or  drinks 
create  an  unnatural  activity  of  the  heart  and  blood-vessels, 
and  are  therefore  injurious  to  them. 

182.  In  the  bilious  temperament,  the  skin  is  brown,  and 
inclining   to  yellow ;  the  hair   is  usually  dark ;   the  form  is 
moderately  full,    but    not  fat;  the  limbs  are  not  gracefully 
rounded,  but  the  muscles  are  well  developed  and  very  strong. 
Men   of  this    class    are   not    very  quick    in    mind  or  body. 
They  are  calm  and  placid  —  not  irritable  in  temper.     They 
have  great  boldness  of  purpose,  energy  in  action,  and  perse- 
verance in  their  undertakings.     They  are  men  who  succeed 
in  their  course  of  life,  because  they  are  cool  and  cautious  in 
their  plans,    and   indefatigable  and  persevering  in  carrying 
them  into  execution.     In  the  higher  and  in  the  lower  walks 
of  life,  they  are  successful. 

183.  Wherever  persons  of  the  bilious  temperament  be- 
gin life,  they  go  up  higher.     There  is  within  them  a  restless 
energy,  that  is  not  content  with  the  present,  whatever  it  may 
be.  Napoleon  Bonaparte  is  a  remarkable  instance  of  this  tem- 
perament ;  Capt.  P.,  who  at  twenty-two  years  of  age  was  an 
hostler,  and  afterward  became  owner  and  commander  of  one 
of  the  largest  steamboats  on  the  Mississippi,  is  another ;  and 
most  of  those  who   in  the  beginning  of  life  were  day-labor- 
ers, without   means  or  friends,  but  afterwards  are  prosperous 
and  wealthy,  and  become   the   leading  men  in  their  towns, 
and  the  governing  men  in  their  respective  business  associa- 
tions, all,  or  nearly  all,  belong  to  this  class,   and   are  of  the 
bilious  temperament.     These  men  neither  need,  nor  are  they 
benefited  by  the  stimulating  diet  of  the  lymphatic,  nor  by 
the  spare  and  cautious  diet  of  the  nervous   and   sanguine. 
Their    temper    and    habits   of  life   generally  imply  a   great 
amount  of  action  of  body  or  mind,   generally  of  both,  and 
consequently  a  great   expenditure   of  material ;  they   need, 
therefore,  a  full  and  generous  diet  of  nutritious  food,  to  sus- 
tain them  in  their  activity. 

184.  Without  supposing  that  any  one  can  tell  exactly  the 
temperament  of  himself,  or  of  his  companions,  yet  one  can 


88  PHYSIOLOGY   AND    HEALTH. 

hardly  fail  to  observe  a  difference  among  his  associates.  One 
is  active  and  sprightly ;  another  inactive  and  dull.  One  is 
excitable  and  irritable;  another  is  slow,  calm,  and  placid. 
One  is  hasty  and  impatient,  quick  to  receive  new  ideas,  or 
eager  to  engage  in  new  plans;  another  is  slow  of  under- 
standing, and  hesitates  about  new  propositions.  These  dif- 
ferences are  very  perceptible,  both  in  men  and  women.  It  is 
easy  to  see,  among  children  at  school,  how  much  quicker  one 
is  than  another  in  learning  his  lessons,  and  how  much  more 
impetuous  and  active  at  his  play.  He  has  not  necessarily 
greater  talent  for  learning,  nor  more  fondness  for  amusement 
than  the  other,  who  is  more  patient  and  slow  at  his  books, 
and  less  hasty  and  boisterous  on  the  playground;  but  his 
talents  and  his  feelings  are  all  more  active.  He  understands 
his  lessons  in  school  more  readily,  but  he  is  not  in  the  end  a 
better  scholar;  he  is  more  ready  in  his  games  of  sport,  but 
he  does  not  play  with  more  skill.  He  requires  a  smaller  in- 
ducement to  begin  a  task  in  the  school-room,  or  a  game  on 
the  playground  ;  but  he  does  not  persevere  so  faithfully  to 
the  end,  as  the  duller  and  slower  boy. 

185.  These  are  differently  affected  by  outward  circum- 
stances, by  affairs  of  life,  by  the  treatment  of  others,  by  grat- 
ifications or  disappointments.  They  are  as  variously  affected 
by  the  matters  which  they  eat  or  drink.  It  is  well  known, 
that  one  man  can  drink  large  quantities  of  strong  spirit 
without  being  visibly  affected,  while  another  can  hardly  take 
a  small  portion  of  wine  without  being  intoxicated.  A  sim- 
ilar difference  follows  the  use  of  stimulating  and  unstimulat- 
ing  food.  What  is  beneficial  to  one  is  injurious  to  another. 
The  sanguine  arid  the  ardent  need  a  cooling  diet.  The  cool 
and  dull  want  meat,  and  other  exciting  food.  The  quick 
and  irritable  should  live  upon  bread,  vegetables,  fish,  and 
such  other  matters  as  will  not  excite  them.  If  they  thus 
regulate  their  diet,  according  to  the  peculiarities  of  their 
constitution,  they  will  be  better  able  to  control  themselves. 
If  they  disregard  these,  and  eat  otherwise,  they  will  give 
strength  to  those  peculiarities  already  too  strong,  and  the 


DIGESTION    AND    FOOD.  87 

lymphatic  will  become  more  sluggish,  and  the  excitable 
will  have  too  high  degree  of  action,  and  run  on  life  too 
rapidly ;  and  thus  both  will  enjoy  less  health,  and  accom- 
plish less,  than  if  they  lived  faithful  to  the  necessities  of 
their  constitution. 


CHAPTER   XX. 

Difference  of  Constitution  in  Childhood  and  old  Age.  —  Food  to  be 
varied  accordingly.  —  The  Active  want  more  stimulating  Diet  than 
the  Inactive.  —  When  Habits  are  changed,  Food  must  change. 

186.  THERE  is  a  difference  of  excitability  in  the  differ- 
ent periods  of  life,  which  should  be  supported  by  a  corre- 
sponding difference  in  the  quality  of  the  food.     In  childhood, 
all  the  powers  of  life  are  more  active,  the  blood  flows  more 
rapidly,  the  nervous  system  is  more  irritable,  and  the  muscles 
more  easily  stimulated  to  action ;  the  feelings  and  passions, 
and  nil  the  motions  of  life,  more  readily  quickened;  but  there 
is  le&s  power  of  endurance,   and  the  energies  are  sooner  ex- 
hausted, than  in  maturer  life.     In  old  age,  all  the  powers  and 
systems  are  in  the  very  opposite  condition.     There  is  a  slug- 
gishness in  all  the  motions,  and  an  inactivity  in  the  limbs : 
and  the  feelings,  the  passions,  are  slow  to  rise. 

187.  There  is  a  wide  difference  between  these  conditions 
of  life ;  and,  if  we  should  attempt  to  support  them  with  food 
of  the  same  quality,  we  should  fail  of  giving  each  its  true 
life  and  strength.     It  is  plain  that  the  elastic  period  requires 
a  mild   and  soothing   diet,  while  the   inactive  period  needs 
more  stimulating  food.     Children  then  want  milk,  bread,  and 
mostly  vegetable  food  ;  and,  if  they  add  meat  to  this,  it  should 
be  of  the  milder  kinds,  such  as  fish  and  fowl,  rather  than  beef 
and  mutton.     But  old  men  need  more  meat,  and  that  of  the 
most  stimulating  and  nutritious  kinds. 

188.  The  habits  of  the  individual  have  an  important  bear- 
ing upon  the  quality  of  food.     Those  can  bear  the  greatest 


88  PHYSIOLOGY    AND    HEALTH. 

stimulation  who  have  the  greatest  activity,  and  whose  exer- 
cise opens  the  freest  outlet  for  their  nervous  energies.  On 
the  other  hand,  the  habitually  indolent  and  inactive,  whose 
nervous  energies  are  not  freely  expended,  do  not  bear  stimu- 
lation easily,  because  they  have  less  outlet  for  the  quickened 
flow  of  vitality.  The  laborious  and  the  active  should  eat 
more  stimulating  food  than  the  sedentary  and  the  idle. 
Farmers,  sailors,  masons,  carpenters,  and  out-of-door  labor- 
ers, want  more  meat ;  while  students,  tailors,  shoemakers, 
and  house-employed  women,  want  more  bread.  The  former 
thrive  best  upon  beef,  mutton,  and  bread  ;  while  the  others, 
when  they  add  meat  to  their  vegetable  food,  do  well  with 
chickens,  fowl,  turkeys,  and  fish. 

189.  Disorders  of  the  stomach  arise  from  neglect  of  this 
caution.     While   men    are   engaged    in    hard   labor    abroad 
they  have  good  appetite  and  vigorous  digestion,  and  very 
properly  eat  stimulating   food ;    but  if  they  leave  their  la- 
borious   occupations,    and    become   jewellers,   shoemakers, 
scholars,  or  merchants,  or  engage  in  any  light  employment, 
their  lives,  from  being  the  most  laborious  and  active,  become 
quiet  and  often  sedentary.     They  have  less  change  in  their 
vital  particles,  and,  of  course,  less  nutritive  want  and  di- 
gestive power. 

190.  If,  now,  these  men  do  not  change  their  diet  with 
their  habits  of  exercise,  their  digestive  powers  begin  to  falter, 
and  then  they  feel  oppressed  after  eating.     They  eat  with  less 
satisfaction,  and   do   not   have   the   sensations  of  ease  and 
comfort  after  their  meals.     They  are  dull,  and  disinclined 
to  go  to  their  usual  employments,  or  their  books,  or  their 
accounts. 

191.  When  one  exchanges  a  light  for  a  laborious  occupa- 
tion, he  increases  his  expenditure  of  particles,  and  conse- 
quently the  demands  for  nutrition.     His  stomach  gradually 
gains  power,  and  his  appetite  craves  more  food  to  meet  the 
new  habit  of  life.     A  hard  student  at  Westford  Academy, 
in  1822,  became  dyspeptic  and  feeble.     He  had  little  appe- 


DIGESTION    AND    FOOD.  89 

the,  and  digested  his  small  portions  of  food  with  difficulty. 
He  left  his  studies,  and  went,  as  a  common  sailor,  to  South 
America.  At  first,  he  performed  little  of  the  light  labor  of 
the  ship,  and  ate  sparingly,  as  he  had  on  land ;  but  his 
strength  of  body  and  power  of  digestion  increased,  and,  after 
a  few  months,  he  was  able  to  do  a  sailor's  work,  and  eat  a 
sailor's  allowance.  He  ate  the  heavy  and  stimulating  food* 
of  the  ship,  —  the  salt  meat  and  hard  bread,  —  with  good 
relish  and  good  digestion,  and  felt  no  oppression  afterward. 


CHAPTER   XXI. 

Digestibility  and  Nutritiousness  of  Food  not  identicaj. —  Food  easily 
digested  not  always  best  for  Invalids.  —  Condiments  excite  and 
exhaust. —  Sensibility  of  Stomach.  —  Alcohol  and  Wines  exhaust 
still  more.  —  No  single  Rule  of  Diet  to  govern  all  Men. 

192.  THERE  are  two  things  to  be  considered  in  regard  to 
all  kinds  of  food;  these  are,  1st, the  digestibility  —  the  ease 
or  the  difficulty  of  being  converted,  by  the  stomach  arid  its 
gastric  juice,  into  chyle;  and,  %d,the  quantity  of  nutriment 
contained  in  them.     And  these  are  not  necessarily  one  and 
the  same.     One  article  of  diet  may  be  very  easily  digested, 
but  contain  very  little  nutriment.     On  the  other  hand,  some 
articles    are   highly   nutritious,  yet  are  very  difficult  to  be 
digested.     Perhaps  no  food  contains  more  of  the  nutritive 
principle  than  oil,  yet  few  kinds  require  longer  time  to  be 
converted  into  chyme. 

193.  That   food   which   is   most   easily   digested    is  not 
always  the  most  suitable  for  the  sick  and  feeble.     Beef  and 
mutton  are  much  more  readily  changed  by  the  action  of  the 
stomach  than  gruel.     But  they  are-also  much  more  stimulat- 
ing to  the  system  ;  and,  if  eaten  by  the  sick  and  the  convales- 
cent, they  might  excite  fever,  perhaps  a  return  of  the  disease. 
But  gruel,  and  bread,  which  may  require  a  longer  time  and 
a  greater  labor  of  the  stomach  to  digest  them,  do  not  excite 


90  PHYSIOLOGY    AXD    HEALTH. 

the  circulation  of  the  b!occl,  nor  produce  fever.  Dangerous 
and  even  fatal  consequences  sometimes  ensue  from  a  neg- 
lect of  this  distinction. 

194.  When   we  rub  the   skin  with   pepper,   mustard,    or 
spirit,  it  creates  irritation ;  the  veins  and  arteries  enlarge ; 
the  blood  flows  to  the  place  in  unusual  abundance;  there  is 
an  increased  heat  in  the  spot,  and  the  surface  is  red;  there 
are  greater  action  and  quicker  life ;  but   these  effects   soon 
cease;    and  then  the  skin  is  pale,  the  circulation  is  more 
languid,  and  the  life  of  the  part  is  more  dormant,  as  unusual 
action  of  the  muscles  leaves  fatigue  behind.     These  are  the 
natural  effects  of  stimulation:    first,  increased  activity;   arid 
next,  increased  languor;  for  all  unnatural  excitement  of  the 
natural  actions  of  the  living  system  is  followed  by  a  corre- 
sponding depression. 

195.  The  same  takes  place  in  the  stomach  from  the  use 
of  all  condiments,   such  as  spices,  pepper,  mustard,  with  our 
food.     The  stomach  is  stimulated,  the  circulation  of  blood 
in  its  walls  is  quickened,  the  gastric  juice  flows  more  readily, 
and  digestion  begins  more  promptly.     But  soon  this  unnatu- 
ral activity  ceases ;  and  then  it  falls  below  its  natural  stand- 
ard, and  digestion  is  finally  retarded.     This  is  the  effect  of 
once  using  the  stimulating  condiments ;  but,  if  this  use  be 
continued  and   often   repeated,  the  power  of  the    stomach, 
from   frequent  excitement  and  fatigue,  becomes   somewhat 
worn,  and  the  organ  is  permanently  enfeebled.     To  a  healthy 
stomach,   then,    condiments    and    stimulants,    are   not   only 
unnecessary,   but  injurious.     They  give  no  strength;   they 
only  quicken  the  action  and  expenditure  of  power  already 
existing. 

196.  These  enfeebling  effects  follow  the  stimulation  of 
wines  and  spirits  even  more  than  that  of  spices.     Alcohol  is 
more  speedy  in  its  action,  both  of  excitement  and  exhaustion. 
Dr.  Beaumont  saw  that  St.  Martin's  stomach  was  reddened 
after  drinking  spirit,  and  sometimes  the  covering  of  the  inner 
coat  peeled  off,  and  left  spots  of  canker  upon  the  surface. 
The  remote  result  of  this  drinking  is  more  severe  and  dan- 


DIGEbTION    AND    FOOD.  91 

grerous  than  that  of  condiments.  The  stomach  gradually 
loses  its  power,  until  it  becomes  incurably  dyspeptic,  and  la 
unable  to  digest  the  ordinary  food. 

197.  The  use  of  all  stimulants,  both  of  spices  and  alcohol, 
at  first  sharpens  and  then  destroys  the  natural  sensibility  of 
the  tongue  and  mouth.     The  healthy  appetite  of  those  who 
are  unused  to  stimulants  is  simple,  and  wants  simple  things. 
They  have  a  refined  taste,  and  nice  discrimination  of  the 
different  flavor  of  various  kinds  of  food,  and  a  keen  relish 
for  what  they  eat,  although  it  is  neither  prepared  with  spice, 
nor  accompanied  with  spirits  or  wine.     But  those  who  are 
accustomed  to  highly-seasoned  dishes  are  not  satisfied  with- 
out them.     All  simple  dishes  are  insipid.     Their  taste  is  so 
blunted   that  these   do  not  excite  it.     And,  in  the  old  and 
habitual  drunkard,  this  sensibility  is  so  deadened  that  nothing 
short  of  a  very  active  or  even  pungent  stimulant  will  reach 
and  satisfy  it. 

198.  A   man  who   for  years   had  drunk  tea  and  coffee, 
and  occasionally  wine,  and  habitually  eaten  spices,  suddenly 
ceased  to  use  them,  and  drank  only  milk  and  water,  and  ate 
no  other   condiment  than   salt   with  his   food.     After  eight 
months'  practice  of  his  simple  diet,  the    sensibility   of  his 
tongue  became  so  exalted,  and  he  gained  so  nice  a  discrimi- 
nation of  taste,  that  he  could  distinguish  and  enjoy  the  vari- 
ous flavor  of  water  from  different  wells,  as  readily  as  he  had 
distinguished  between  the  various  kinds  of  wine,  tea,  and 
coffee.     The  enjoyment  of  the  mere  taste  and  appetite  is  not 
in  proportion  to  the  stimulating  power  of  what  we  eat  and 
drink,  but  in  the  ratio  of  the  quickness  of  the  sensibility. 
And  the  water-drinker,  while  in  the  mere  act  of  drinking, 
enjoys  his  pure  water  more  than  the  wine-drinker  does  his 
wines,  or  the  spirit-drinker  his  stronger  and  more  stimulat- 
ing drinks.     "  Happy  are  the  young  and  healthy,"  says  the 
shrewd  Dr.  Kitchener,  "  who  are  wise  enough  to  be  con- 
vinced that  water  is  the  best  drink,  and  salt  the  best  sauce." 

199.  From  this  examination  of  the  structure   and   uses 
of  the  digestive  organs,  and  of  their  purposes,  powers,  and 


92  PHYSIOLOGY    AND    HEALTH. 

liabilities,  we  learn  that  the  stomach  performs  some  of  the 
most  delicate  operations,  and  effects  some  of  the  most  won- 
derful changes,  in  nature;  and  that  it  requires  the  aid  of 
the  intelligent  hand  to  supply  its  wants,  and  fit  the  sup- 
plies to  its  necessities.  There  is  no  human  instinct  to  be 
our  unerring  guide,  and  to  direct  us  what  and  how  much 
we  shall  eat  or  drink.  The  living  machinery  within,  and 
the  dead  material  without  our  bodies,  are  prepared  for  our 
use ;  and  the  law  of  nature  is  declared  to  us  for  our  govern- 
ment. This  we  are  required  to  read  and  to  understand, 
before  we  can  perform  our  part  in  the  sustenance  of  our 
frames. 

200.  This  is  not  a  law  of  appetite,  that  -directs  us  always 
to  eat  when  we  are  hungry,  and  take  such  kinds  of  food, 
and  as  much  of  it,  as  the  palate  craves.     Nor  is  it  a  law  of 
convenience,  that  allows  such  food  as  chance  or  caprice  may 
place    before    us.      But   nature   has    established    for   every 
man  a  law  which  must  govern  his  nutrition.     This  law  is 
founded  upon  the  structure  of  his  digestive  organs,  the  wants 
of  his  frame,  his  temperament,  his  age,  and  his  habits  of 
exercise.     Every  individual  must  understand  these   general 
principles,   which   have   been  described   in  this  book,   and, 
applying  them  to  ^imself  and  his  circumstances,    he  must 
determine  what  food,  and  how  much,  will  meet  the  necessi- 
ties of  his  own  body. 

201.  In  this  matter,  as  there  are  great  varieties  of  men  and 
of  external  circumstances,  so  there   is  no  one  rule  of  diet 
that  will  apply  to  all  mankind.  '  All  the  differences  of  men 
must  be  supplied  with  corresponding  differences  of  nutriment. 
Those  codes  of  diet  which  are  laid  down  for  the  government 
of  all  men,  of  every  variety  of  temperament,  and  habit,  and 
location,  and  which  attempt  to  sustain  all  men  with  the  same 
aliment,  are  absurd,  and  fail ;  for  every  man,  or  every  class  of 
men,  have  their  peculiar  powers,  and  their  peculiar  wants ; 
and  if  they  disregard  these,  and  endeavor  to  support  life  by 
any  other  rule,  they  will  not  fully  accomplish  the  purpose  of 
eating. 


CIRCULATION    OF    THE    BLOOD.  93 


PART  II. 
CIRCULATION  OF  THE  BLOOD  AND  NUTRITION. 


CHAPTER  I. 

Apparatus  of  Circulation.  —  Heart.  —  Structure  and  Divisions.  — 
Valves. — Arteries.  —  Aorta.  —  Subclavian,  carotid,  facial  arteries. 
—  Branches  in  the  lower  limbs. 

202.  THE   chyle,  or  the  nutritious  part  of  the  digested 
food,  is  tarried  from  the  digestive  organs,  in  the  abdomen, 
through  the   absorbent  mouths,  and  the  lacteal  tubes,  and 
great  lacteal  duct,  to  the  great  veins  near  the  heart.     There 
it  is  mixed  with,  and  becomes  a  part  of,  the  blood.     This 
blood  is  to  undergo  certain  changes  in  the  lungs,  and  then 
it  is  to  be  distributed  to  all  the  parts  of  the  body. 

203.  The  apparatus  for  this  distribution  or  circulation  of 
the  blood  consists  of  the  heart,  or  central  organ  of  motion ; 
the  arteries,  which  carry  all  the  blood  out  of  the  heart  to 
the  lungs  and  to  the  various  parts  of  the  body ;  the  capillary 
vessels,  in  which  nutrition  takes  place ;  and  the  veins,  which 
carry  the  blood  back  to  the  heart. 

2.04.  The  heart  (Fig.  VII.)  is  a  hollow,  muscular  organ,  or 
bag,  composed  of  fibrous  substance,  like  lean  meat.  It  is 
capable  of  contraction  and  expansion,  like  the  muscular  coat 
of  the  stomach.  When  it  contracts  it  diminishes  its  internal 
cavity,  and  presses  out  the  fluid  contents  or  blood  that  is 
within  it.  When  it  relaxes,  its  cavity  is  enlarged  and  allows 
other  fluid  or  blood  to  flow  into  it. 

205.  The  heart  is  placed  in  the  centre  of  the  chest,  be- 
tween  the  two  lungs,  (Fig.  V.  c.)  Its  larger  end  is  upward, 


94 


PHYSIOLOGY    AND    HEALTH. 


and  behind  the  breast-bone.  The  smaller  end  or  apex  is 
downward,  and  turned  toward  the  left.  When  the  heart 
contracts,  to  send  the  blood  out,  the  apex  is  thrown  forward 
and  strikes  against  the  ribs  of  the  left  side,  near  the  breast- 
bone, wnere  the  beating  is  very  easily  felt 

FIG,  VII.     Heart. 


f,  Artery  carrying  the  blood 
from  the  right  ventricle  to  the 
lungs. 

g,  k,  Great  veins  carrying  the 
blood    from   the    body    to    the 
heart. 


ct,  Right  auricle. 

b,  Left  auricle. 

c,  Right  ventricle. 

d,  Left  ventricle. 

e,  Great    artery   carrying    the 
blood  from  the  left  ventricle  to 
the  body. 

206.  The  internal  cavity  of  the  heart  is  divided  by  a  par- 
tition wall  of  flesh  (Fig.  VIII.  c)  into  two  apartments, 
one  on  the  right,  and  one  on  the  left.  This  separation  of 
the  two  sides  of  the  heart  is  complete.  There  is  no  passage 
way  through  this  wall,  and  consequently  no  direct  communi- 
cation between  the  two  apartments.  They  are  sometimes 
described  as  two  hearts  united  together. 


CIRCULATION    OF 


96 


Fm.  VIE.     Heart  laid  open.     View  of  the  four  Chambers  of 
the  Heart. 

a.  Left  ventricle. 

b    Right  ventricle. 

r  Partition  wall  between  the 
two  sides. 

«?.  Right  auricle. 

e.  Left  auricle. 

/,  g.  Partitions  between  the  au- 
ricles and  ventricles. 

h,  h.  Great  artery  leading  from 
the  left  ventricle  to  the  whole 
body. 

i,  i.  Great  vein  carrying  the 
blood  to  the  heart  from  the  whole 
body. 

k,  k.  Arteries  leading  to  the 
lungs. 

I,  i.  Veins  leading  from  the  lungs 

The  arrows  show  the  course  of  the  blood  through  the  heart. 

207.  Each  of  the  two  grand  divisions  of  the  heart  is  again 
divided  into  two  smaller  chambers.     On  the  left  side,  the 
one  above  (Fig.  VIII.  e)  is  called  the  left  auricle,  and  the 
one  below,  (Fig.  VIII.  a,)  the  left  ventricle.     On  the  right 
side,  the  chamber  above  (Fig.  VIII.  d)  is  called  the  right  au- 
ricle, and  the  one  below,  (Fig.  VIII.  b,)  the  right  ventricle. 
These  make  four  separate  chambers  in  the  heart.     There  is 
no  communication  between  the  two  auricles,  nor  any  between 
the  two  ventricles ;  but  there  is  a  passage-way  on  each  side, 
opening    from   the    auricle   above   to  the  ventricle   below, 
through  which  the  blood  passes  from  the  upper  to  the  lower 
chamber. 

208.  The  blood  flows  from  the  auricle  to  ths  ventricle,  but 
not  backward  from  the  ventricle  to  the  auricle.      There  are 
valves  placed  at  these  passage-ways  in  the  heart,  which  open 
to  allow  the   blood  to  pass  downward,  but  they  close,  and 
prevent  its  passing  upward.    These  valves  act  on  the  principle 
of  the  valve  in  the  common  pump  box,  which  opens  when  the 
water  below  presses  upward,  and  allows  it  to  pass  through  ; 


96  PHYSIOLOGY    AND    HEALTH. 

but  it  closes  again  when  the  water  above  presses  downward, 
and  prevents  its  return  to  the  well. 

209.  The  heart  is   the  centre   of  the  circulating  system. 
It  sends  all  the  blood  to  the  whole  body  through  the  arteries, 
and  receives  it  back  again  through  the  veins.     There  are  two 
sets  of  these  blood  vessels,  each  consisting  of  arteries  and 
veins.     One  set  begins  at  the  heart  and  extends  through  the 
whole  body.     The  other  set  reaches  from  the  heart  to  the 
lungs.     The  arteries  open  from  the  ventricles  or  lower  cham- 
bers of  the  heart,  and  carry  the  blood  out.     The  veins  open 
into  the  auricles  or  the  upper  chambers  of  the  heart,  and 
carry  the  blood  back. 

210.  The  arteries  are  round  tubes.     They  are  firm  in  their 
structure,  and   retain   their  cylindrical    form   when    empty. 
They  are  composed  of  three  coats.     The  outer  coat  is  dense 
and  strong,  and  is  the  principal  means  of  resistance  to  pres- 
sure.    The'  middle  coat  is  thick  and  elastic,  and  expands 
when  the  blood  flows  in,  and  contracts  when  it  flows  out. 
The  inner  coat  is  very  delicate,  and  forms  a  polished  surface, 
on  which  the  blood  flows  easily.     The  arteries  have  the  same 
structure  throughout  the  body.     There  is  a  valve  between 
the  ventricle  and  the  aorta,  which  allows  the  blood  to  pass 
from  the  heart  into  the  artery,  but  not  to   flow  backward 
from  the  vessel  into  the  heart. 

211.  One  large  artery,  called  the  aorta,  leads  out  from  the 
left  ventricle  upward,  (Fig.  VII.  e,  Fig.  IX.  c,  d,  e,)  and  then 
turns  downward,  (Fig.   IX.   d.)     It   passes   then  along   the 
back-bone,   through    the   chest    and   the    abdomen.      Great 
branches  pass  out  from  this  artery  to  the  various  parts  of  the 
body.     Two  branches,  called  the  carotids ,  (Fig.  IX.  /*,  f,) 
pass  off  from  the  arch  and  go  to  the  head,  one  on  each  side 
of  the  neck.     Two  branches,  called  the  subclavians,  (Fig. 
IX.  g,  g,)  go  to  the  arms  and  hands.     While  passing  through 
the  chest,  the  aorta  sends  branches  to  the  walls  of  the  chest, 
(Fig.  IX.  A,  h.)     In  the  abdomen,  the  aorta  sends  the  cceliac 
artery  to  the  stomach,  the  hepatic   artery  to  the  liver,  the 
renal  arteries  to  the  kidneys,  &,c.,  and  other  branches  to  the 


CIRCULATION    OF    THE    BLOOD. 


97 


various  organs  in  that  region.  At  the  lower  part  of  the 
abdomen,  the  aorta  divides  (Fig.  XI.)  into  two  branches, 
(Fig.  XL  e,  e,)  which  pass  through  the  groins  and  all  the 
limbs  below. 

FIG.  IX.    .Aorta  and  Branches  in  the  Chest. 


a,  b,  Heart. 

c,  Ascending  aorta. 

d,  Arch  of  the  aorta. 

e,  Descending  aorta. 

/,  /,   Carotid  arteries 
going  to  the  head. 

ff,  g,  Subclavian   arte- 
ries going  to  the  arms. 

A,  h,   Branches   going 
to  the  chest. 

i,  i,  Branches  to  the 
right  and  left  lung. 

k,   Great  artery  going 
to  the  lungs. 


212.  The  subclavian  arteries  (Fig.  IX.  g-,  g)  pass  from  the 
arch  of  the  aorta,  and,  extending  under  the  collar  bones  and 
through  the  arm-pits,  they  reach  the  arm ;  at  the  elbows  they 
divide  into  two  main  branches.     One  of  these  can  be  felt  at 
the  wrist,  near  the  root  of  the  thumb.     These  arteries  send 
numberless  little  branches,  which  reach  all  the  flesh  of  the 
arms  and  hands. 

213.  The  carotid  arteries  passing  up  by  the  sides  of  the 
neck,  can  be  felt  near  the  windpipe.     At  the  top  of  the  neck 
they  divide  into  two  branches,  one  of  which  passes  through 
the  skull,   and   is   distributed   to   the   brain.     The   arteries 

9 


98  PHYSIOLOGY    AND    HEALTH. 

and    branches  ramify  throughout  all    the  substance  of   this 
organ. 

The  outer  branch  of  the  .carotid  goes  to  the  outside  of 
the  head  and  to  the  face.  It  sends  branches  to  the  forehead, 
the  cheeks,  the  chin,  the  lips,  and  the  other  parts  of  the  face 
All  these  organs  are  thus  supplied  very  abundantly  with  blood 
by  these  vessels  and  their  numberless  little  branches.  (Fig.  X.) 

FIG.  X.    Arteries  of  the  Face. 


214.  The  aorta  is  divided  in  the  lower  part  into  two  great 
branches,  (Fig.  XL  e,  e.)  These  two  branches  pass  through 
the  groins,  where  they  are  called  inguinal  arteries,  and  thence 
into  the  thighs,  where  they  are  the  femoral  arteries  ;  passing 
downward,  they  divide,  and  send  branches  to  the  flesh  of  the 
lower  limbs,  until  the  legs,  the  feet,  and  the  toes  are  sup- 
plied with  them. 

All  these  arteries  in  every  part  of  the  body  are  divided 
and  multiplied  as  they  go  from  the  heart,  and  their  num- 
berless small  branches  are  distributed  into  every  part  of 
the  flesh  in  all  the  organs  and  regions  of  the  body.  Thus 
all  the  parts,  organs,  and  textures  are  supplied  with  blood 
for  their  nourishment. 


CIRCULATION    OF    THE    BLOOD. 


99 


FIG.  XL    Arteries  of  the  whole  Body. 


a,  Heart. 

6,  c,  c.  Aorta. 

d,  Division  of  aorta. 

e,  <?,  Inguinal  arteries. 


/,  /,  Subclavian  arteries. 
g,  g,  Carotids. 
h,  h,  Branches  in  the  arms. 
t,  t,  t,  Branches  in  legs  and  feet. 


100 


PHYSIOLOGY   AND   HEALTHS 


CHAPTER  II. 

Veins.  —  Distribution.  —  Capillaries.  —  System  of  general  Circula- 
tion. —  Situation  of  Arteries  and  Veins.  —  Pulmonary  Arteries  and 
Veins.  —  Double  Circulation. 


FIG.  XII.    Greed  Veins. 


a,  Heart. 

b,  Ascending  vena  cava. 

c,  c,  Subclavian  veins. 

d,  d,  Brachial  veins,  in  the  arms. 

e,  e,  Veins  from  the  outside  of  the 
head. 

f>  />  Veins  from  the  brain. 

g,  Descending,  or  abdominal  vena 
cava. 

h,  h,  Veins  from  the  kidneys. 

i,  it  Great  branches  of  veins  in  the 
groins. 

k,  k.  Veins  from  the  lower  extrem- 
ities. 


'  215.  The  veins  also  connect  the 
heart  with  every  part  of  the  body. 
Their  coats  are  thinner  and  softer 
than  the  arteries.  They  collapse 
when  they  are  empty.  They  are 
easily  compressed,  as  can  be 
shown  by  pressing  the  veins  on 
the  back  of  the  hand.  They 
have  valves,  which  open  and  allow 
i,he  blood  to  pass  toward  the 
heart,  but  close  and  prevent  it 
flowing  backward. 

216.  One  large  vein,  the  vena 
cava,  opens  into,  the  heart,,  and 
carries  all  the  blood  of  the  body 
into  it.  The  upper  part  of  this  vein,  the  vena  cava  ascen- 
dens,  extends  upward,  and  sends  branches  to  the  head  and  the 
arras.  The  lower  part,  the  vena  cava  descendens,  passes 


CIRCULATION    OF    THE    BLOOD. 


101 


through  the  abdomen,  along  the  side  of  the  aorta,  and  sends 
branches  to  the  organs  of  digestion,  &/c.,  and  to  the  lower 
limbs. 

FIG.  XIII.     Veins  of  the  whole  Body. 


a,  Heart. 
c,  Vena  cava. 

d,  Division. 

e,  e,  Inguinal  veins. 
,  <7,  Jugular  veins. 

h,  h,  Branches. 


217.    The  jugular  veins  pass  upward  from  the  upper  great 
vein,  through  the  sides  of  the-neck,  to  the  head.     They  send 
9** 


102  PHYSIOLOGY   AND    HEALTH. 

branches  to  the  brain  within,  and  to  the  scalp  and  the  parts 
of  the  face  without  the  skull.  The  subclavian  veins  (Fig. 
XII.  c,e)  also  pass  off  from  the  upper  great  veins.  They  go 
through  the  arm-pit,  and  send  numberless  branches  to  the 
arms  and  hands.  The  great  abdominal  cava  sends  branches 
to  the  stomach,  liver,  alimentary  canal,  kidneys,  &c.,  and 
finally  it  is  divided  (Fig.  XII.  *,  i)  into  two  great  veins,  which 
with  their  branches  reach  all  the  parts  of  the  lower  limbs 
and  feet,  (Fig.  XIII.  h,  h.) 

218.  All  these  veins,  like  the  arteries,  are  divided  and 
multiplied  into  branches  almost  infinitely  small  and  numer- 
ous, and   thus  they  reach  every  part  of  the  animal   body, 
(Fig.  XIII.) 

219.  The  arteries  are  said  to  begin  at  the  heart  with  one 
large  trunk,  the  aorta,  (Fig.  XL  &,)  and  to  end  in  all  the  near 
and  the  remote  parts  of  the  body  in  almost  infinite  numbers 
of  minute  tubes.     The  veins,  on  the  contrary,  are  said  to 
begin  in  the  flesh  of  all  the  parts  of  the  body,  with  tubes 
almost  infinitely  small  and  numerous,  similar  to  the  termi- 
nating arteries,  and  end  in  one  large  trunk,  the  vena  cava, 
at  the  heart,  (Fig.  XIII.)     These  trunks  meet  at  the  heart 
with  their  large  trunks,  and  again  they  nearly  meet  through- 
out the  whole  body  with  their  minute  extremities. 

220.  The  capillary  system  of  blood-vessels  is  placed  be- 
tween the  minute  extremities  of  the  'arteries  and  the  minute 
ends  of  the  veins.     They  are  called  capillaries  from  their 
hair-like  minuteness.     They  are  even  smaller  than  this,  for 
they  cannot  be  seen  by  the  eye.     They  are  spread  in  every 
part  and  every  organ  of  the  body.     They  form  the  connect- 
ing link  between  the  arteries  and  the  veins,  and  carry  the 
blood  from  one  to  the  other. 

221.  The  system  of  the  general  circulation  of  the  blood  if 
thus  composed  of  the  heart,  the  arteries,  the  capillaries,  and 
the  veins.     The  blood  flows  out  from  the  ventricle  on  the  left 
side  of  the  heart  into  the  aorta.     It  passes  through  this  large 
artery  into  the  large  branches,  and  thence  into  the  smaller 
branches,  and  then  through  the  minute  branches  into  the 


CIRCULATION    OF    THE    BLOOD.  103 

capillaries,  in  every  part  of  the  body.  From  these  vessels  the 
blood  flows  into  the  minute  extremities  of  the  veins,  and 
thence  into  the  larger  branches,  and  finally  into  the  great 
vena  cava,  which  pours  the  blood  into  the  right  auricle  of 
the  heart. 

22*2.  The  arteries  carry  the  nutritious  blood  to  support  the 
life  of  the  textures.  If  they  are  wounded,  serious  conse- 
quences follow,  and  they  are  not  very  readily  healed.  They 
are  therefore  placed  deeply  within  the  flesh,  where  they  are 
protected  from  injury.  Some  of  them  approach  the  surface, 
and  their  pulsations  can  be  felt  at  the  wrist,  and  at  the  sides 
of  the  neck,  and  on  the  temple. 

223.  The  veins  carry  the  impure  and  wasted  blood.     They 
suffer  less,  and  are  more  easily  healed,  than  the  arteries  when 
injured.     Their  great  trunks  are  placed*  near  the  great  arte- 
ries, but  their  branches  are  situated  nearer  to,  and  more  of 
them  on,  the  surface,  than  the  arterial  branches.     They  are 
seen  on  the  back  of  the  hand  and  on  the  arms ;  and  sometimes 
they  enlarge   and  become  very  troublesome  on  the  skin  of 
the  lower  limbs.     Bleeding  is  usually  performed  by  opening 
a  vein  of  the  arm*. 

224.  The  blood  passes  out  from  the  left  side  of  the  heart 
through  the  arteries  to  the   body,  and  returns  through  the 
veins  to  the  right  side  of  the  heart.     These  two  sides  are 
separated   by  an  impassable  wall,  (Fig.    VIII.    c.)      Before 
the  blood  can  reach  the  left  side  of  the  heart,  it  must  pass 
through  the  lungs.     This  passage  of  the  blood  through  the 
lungs  constitutes  what  is  called  the  pulmonary  circulation. 

225.  The  pulmonary  artery  passes  out  from  the  right  ven- 
tricle, (Fig.  VIII.  6,)   and  divides  into  two  branches,  (Fig. 
VIII.  k,  &,)  one  of  which  goes  to  the  right  lung,  and  the 
other  to  the  left  lung.     These  divide,  and  finally  spread  their 
minute  branches    throughout   the    substance  of  the  lungs. 
The  pulmonary  veins  begin  very  minute  in  all  the  parts  of 
the  lungs,  where  the  little  arteries  terminate.     These  little 
vessels  unite  again  and  again,  until  they  form  one  large  vein 


104 


PHYSIOLOGY    AND    HEALTH. 


in  each  lung,  and  then  join  together  and  enter  the  auricle 
on  the  left  side  of  the  heart. 

FIG.  XIV.    Double  Circulation  of  the  Blood. 


The  arrows  show  the  course  of  the  blood. 

226.  These  two  sets  of  vessels  constitute  what  is  called  the 
double  circulation.  The  J^lood  is  in  the  left  auricle,  (Fig 
XIV.  a,)  and  passes  thence  downward  to  the  left  ventricle, 


CIRCULATION     OF    THE    BLOOD.  105 

(Fig.  XIV.  b;)  thence  it  flows  through  the  aorta,  (Fig. 
XIV.  c,)  the  large  branches  of  the  arteries,  (Fig.  XIV.  c?,  e,) 
and  the  minute  branches  of  the  arteries  in  all  the  parts  of 
the  body,  (Fig.  XIV.  /,  /,  /,  /,)  into  the  capillaries,  (Fig. 
XIV.  g,  g,  g,  g.)  Thence,  again,  the  blood  flows  into  the 
minute  veins,  (Fig.  XIV.  h,  A,  A,  A,)  and  through  the  larger 
veins,  (Fig.  XIV.  z,  &,)  back  to  the  auricle  of  the  right  side 
of  the  heart,  (Fig.  XIV.  /.) 

This  is  the  general  circulation,  which  carries  the  blood 
from  the  left  side  of  the  heart  through  the  whole  body  and 
back  to  the  right  side  of  the  heart. 

Next,  the  blood  flows  from  the  right  auricle  (Fig.  XIV.  I) 
to  the  right  ventricle,  (Fig.  XIV.  m.)  Thence  it  passes 
through  the  great  pulmonary  artery  (Fig.  XIV.  n)  and  the 
great  branches  of  the  right  and  left  lungs  (Fig.  XIV.  o,  o) 
into  the  minute  pulmonary  branches,  (Fig.  XIV.  p,  p.) 
From  these  it  flows  into  the  minute  pulmonary  veins,  (Fig. 
XIV.  q,  £,  £,  y,)  and  through  the  great  pulmonary  veins 
(Fig.  XIV.  r,  r)  into  the  auricle  of  the  left  side  of  the  heart, 
(Fig.  XIV.  a.) 

This  is  the  pulmonary  circulation,  which  carries  the  blood 
from  the  right  side  of  the  heart  through  all  the  lungs,  and 
back  to  the  left  side  of  the  heart. 


CHAPTER    III.- 

Action  of  the  Heart.  —  Motion  of  the  Blood  in  the  Arteries.  — 
Quantity  and  Flow  of  Blood.  —  Rate  of  Pulsation  varies  with  Cir- 
cumstances.—  Exercise.  —  States  of  Mind  and  Feelings.  Local 
Circulation  varies.  — We  do  not  govern  Circulation,  but  we  may 
disturb  it. 

227.  THESE  organs  of  circulation  are  admirably  contrived 
for  their  purpose.  The  muscular  texture  of  the  heart 
enables  it  to  confact  upon  its  contents,  and  expel  them  with 


106  PHYSIOLOGY    AND    HEALTH. 

force  sufficient  to  send  them  through  the  arteries  to  the 
farthest  extremity  of  the  frame.  The  power  of  the  heart  is 
not  easily  measured.  Some  have  supposed  that  it  could 
exert  a  force  equal  to  that  which  would  be  necessary  to  raise 
several  thousand  pounds  ;  while  others  have  estimated  it  to 
be  equal  only  to  a  few  ounces. 

228.  The  veins  are  continually  pouring  their  blood  into 
the  right  auricle,  or  upper  chamber.     As  soon  as  this  is  full, 
it  contracts,  and  empties  its  contents  into  the  right  ventricle, 
or  chamber  below.     In  the  same  manner,  when  the  pulmo- 
nary veins  fill  the  left  auricle,  this  presses  the  blood  into  the 
chamber  below  ;   and  then  this  lower   cavity  contracts  and 
forces  it  into  the  arteries,  and  through  them  to  the  body. 

229.  This  movement  of  the  blood  is  always  forward.    The 
great  vein  pours  its  blood  into  the  right  auricle.     When  this 
upper  chamber  is  filled,  it  contracts  upon  its  contents,  arid 
"  the  reflux  of  the  blood  into  the  veins  is  prevented  by  the 
valves  with    which  they  are  furnished ; "    but  at  the    same 
time  the  valve  between  this  cavity  and  the  ventricle  below  is 
opened,  and   the  blood  finds  free  passage  through  it.     When 
this  lower  chamber  is  filled  and  contracts,  the  last  valve  is 
closed,  and  the  fluid  has  no  way  of  going  back  to  the  upper 
chamber ;  but  then  the  valve  between  the  ventricle  and  the 
artery  opens  to  allow  the  blood  to  enter  this  tube,  and  closes 
again  as  soon  as  the  artery  is  full ;  so  that  the  blood  cannot 
go  back  to  the  heart.     In  the  same  manner,  the  valves  on 
the  left  side  of  the  heart  open  to  allow  the  blood  to  pass 
from  the  veins  of  the  lungs  to  the  left  auricle,  and  from  the 
auricle  to  the  lower  chamber,  and  again  from  this  chamber 
to  the  arteries   of  the  body  ;  but  at  each  place  they    close 
when  the  next  cavity  is  filled,  and  prevent  the  return  of  any 
fluid 

239.  The  arteries  are  capable  of  expansion .  and  con- 
traction. When  any  thing  is  forced  into  them,  their  coats 
stretch,  and  their  capacity  is  enlarged;  and  when  their  con- 
tents are  removed,  they  contract  again,  and  diminish  theii 
cavity.  These  have  no  valves,  except  that  which  stands 


CIRCULATION    OF    THE    BLOOD.  107 

between  their  great  trunk  and  the  heart;  and  there  is 
nothing  but  this  .to  prevent  the  backward  flow  of  the  blood. 
When  the  left  ventricle  beats,  and  forceps  its  blood  into  the 
arteries,  they  expand  suddenly  to  admit  the  increased  quan- 
tity. All  the  arteries  in  the  body  expand  and  beat  at  very 
nearly  the  same  moment  that  the  heart  beats.  We  can  feel 
this  beating  of  the  arteries  at  the  wrist,  in  the  temples,  the 
sides  of  the  neck,  and  wherever  else  they  come  near  the. 
surface.  Some  can  perceive  it  and  count  their  pulsations  in 
the  brain. 

231.  While  the-heart  is  pressing  the  blood  into  the  artery, 
the  valve  is  opened,  and  the  yessel  expands.     But  as  soon  as 
this  pressure  ceases,  the  valve  closes,  and  the  artery  begins 
to  contract  and  force  the  contents  out  and  onward  through 
its  minute  extremities.     The  blood  is  then  thrown  into  the 
arteries  by  a  muscular  power  of  contraction,  and  it  is  moved 
through  these  vessels  merely  by  the  elastic  power  of  their 
coats. 

232.  The  left  ventricle  of  the  heart  will,  in  a  man  of  av- 
erage size,  contain  about  two  ounces,  or  one   eighth  of  a 
pint.     Every  time  the  heart  beats,  this  cavity  is  filled  and 
emptied ;  therefore,  two  ounces  of  blood  are  forced  into  the 
arteries  at  every  pulsation.     In  ordinary  health,  the  heart  of 
a  man  beats  about  seventy-five  times  in  a  minute,  or  a  little 
more  than  once  in  a  second.     The  quantity  of  blood  in  a 
man  of  average  size  is  estimated  to  be  about  twenty-eight 
pounds,  or  four  hundred  and  forty-eight  ounces ;  and  if  two 
ounces  pass  through  the  heart  at  every  beat,  and  one  hundred 
and  fifty  ounces  every  minute,  then  the  whole  blood  of  the 
human  body  must  pass  through  that  organ,  and  through  the 
whole   system,  once  in  three  minutes.     Seventy  gallons  of 
blood  flow  through  a  man's  heart  in  the  course  of  an  hour, 
and  sixteen  hundred  and  eighty-eight  gallons  in  the  course 
of  a  day. 

233.  This  is  the  usual  rate  of  the  circulation ;  but  it  varies 
with  many  circumstances.     It  is  more  rapid  in  most  diseases 


108  PHYSIOLOGY    AND    HEALTH, 

than  in  health.  The  heart  beats  faster  when  we  are  stand- 
ing  than  when  we  are  sitting,  and  faster  when  sitting  than 
when  lying  down.  The  pulsation  is  more  rapid  in  the  morn- 
ing than  in  the  evening  —  in  females  and  in  children  than 
in  males  and  adults.  All  exercise  increases  the  force  and 
rapidity  of  the  circulation.  The  rapid  and  sometimes  vio- 
lent beating  of  the  heart  when  we  are  running,  or  -making 
great  exertions,  is  familiar  to  every  one. 

234.  While  the  body  or  any  of  its  parts  is  in  motion,  the 
changes  of  the  particles  go  on  more  rapidly,  there  is  more 
waste,  consequently  greater  need  of  nutrition,  (§  127,  page 
61 ;)  and,  to  meet  this  want,  the  heart  quickens  its  action  and 
sends   more  blood  to  the  frame.     There  is  a  great  difference 
between  the  pulse  of  the  active  boy  and  that  of  the  sleeping 
babe.     The  pulsations  of  the  laborer  are  strong  and  hard  ; 
his  heart  forces  the  blood  vigorously  into  the  arteries,  arid 
they  are  distended,  full,  and  feel  hard.     But  the  pulse  of  the 
indolent  man    is   soft    and    feeble.     He  takes  no  exercise ; 
the  changes  of  particles  are  few  and  slow;  there  is  little  waste 
and   little  need   of  nutrition;    and,   consequently/ his   heart 
sends  the  blood  gently,  an'd   oftentimes  feebly,  through  the 
arteries. 

235.  The  circulation  is  affected  by  the  states  of  the  mind 
and  the  feelings.    The  heart  beats  with  more  force  and  rapid- 
ity under  mental  or  emotional  excitement;  than  the  arteries 
beat  with  more  firmness,  and  carry  more  blood.     So  when  a 
man  is  excited  with  anger,  or  stimulated  with  hope,  or  glow- 
ing with  cheerfulness,  or  burning  with  love,  his  blood, flows 
more  freely,  his  system  is  better  nourished,  and  he  is  stronger 
and  more    capable  of  exertion.      The  depressing   passions 
have  the  opposite  effect  of  lowering  the.action  of  the  heart, 
and  the  force  of  the  circulation.     While  a  man  is  suffering 
with  fear,  despair,  sorrow,  or  gloom,  his  heart  beats  more 
feebly,  and  his  blood  flows  more  languidly ;  his  body  is  less 
nourished,  his  strength  is  impaired,  and  he  has  kss  power  of 
labor. 


CIRCULATION    OF    THE     BLOOD.  109 

236.  Although  the   heart  sends  the  blood    by  the   same 
impulse  to  all  the   arteries,  and  all  these  must  then  beat,  al- 
most at  the  same  moment,  and  in  unison,  yet  the  expansion 
and  contraction  of  these  blood-vessels    are  not  always   the 
same  in  all   parts  of  the  body.     Hence  the  blood  may  circu- 
late with  very  different  force  in  various  parts,  and  some  may 
be   supplied  very  freely  while  others  are  but  sparingly  fed 
with  this  fluid.     Local  diseases  create  a  greater  local  circu- 
lation.    When  one  has  a  felon  on  his  finger,  he  feels  the 
arteries  throb  sometimes  violently  in  the  sides  of  that  fin- 
ger, while  the  beating  of  the  arteries  in  the  other  fingers  is 
scarcely  noticed.     Some  suffer  from  cold  feet  in  consequence 
of  feeble    circulation   of  blood   through    those   extremities ; 
others  have  headaches  from  the  too  great  flow  of  blood  to  the 
brain.     The  arteries  are  more  active  in  the  parts  that  are  in 
action.     More  blood  flows  to  the  muscles  during  the  time  of 
labor,  to  the  stomach  during  digestion,  and  to  the  brain  when 
the  mind  is  actively  employed. 

237.  This  beating  of  the  heart,  and  this  pulsation  of  the 
arteries,  are  incessant  during  life.     Day  and  night,  asleep  or 
awake,  this  movement  goes  on,  and  every  part  of  the  frame 
receives  its  supply  of  blood  in  due  season,  without  our  voli- 
tion, and  even  without  our  observation.     The  circulation  of 
the  blood  is  not  submitted  to  our  care,  and  we  are  not  respon- 
sible for  its  work,  as  we  are  for  the  work  of  digestion.     Yet, 
though  we  are  not  called  upon  to  aid  this  function,  we  may 
interfere  for  evil.     We  may,  by  stimulating  food  or  drinks, 
excite  the   heart  too  much    for  health;    or,  by  neglect  of 
proper  exercise,  we  may  suffer  it  to  become  sluggish  in  its 
motions. 

10 


110  PHYSIOLOGY    AND   HEALTH. 


CHAPTER   IV. 

Object  of  Eating  and  Circulation  is  to  nourish  the  Body.  —  AJ1  Ani- 
mal Solids  and  Fluids  formed  out  of  the  Blood.  —  Elementary 
Composition  of  the  Blood  and  Flesh :  nearly  alike  in  all  the  Tis- 
sues, but  differ  in  the  Proportions  of  their  Elements.  —  Nutrition 
takes  Place  in  the  extreme  Vessels,  and  with  unerring  Precision. 
Growth  and  Changes  of  the  Body  are  at  the  Cost  of  the  Blood.— 
The  Atoms  of  the  Body  enjoy  but  a  temporary  Life.  —  When  one 
dies,  it  is  removed.  —  Absorbents. 

238.  As   the  eating  and    digestion  of  the  food  have  .no 
other  object  than  to  supply  the  wants  of  the  blood,  so  the 
motions  of  the  heart,  and  the  circulation  of  the  blood,  are 
for   the  sole  purpose  of  supplying  the  wants  of  the  frame. 
All  the  growth  of  the  body  in  childhood  and  youth,  all  the 
regaining  of  flesh  after  sickness,  all  increase  of  flesh  at  any 
period  of  life,  and  all  the  changes  of  particles,  are  supplied 
by  the  blood.     All  the    tissues    and  secretions  of  the  body, 
various  as  they  are,  —  the   bone,  muscle,    brain,  skin,   fat, 
the  hair  and  the  nails,  the  tears,  the'  saliva,  and  the  perspira- 
tion, — -  are  all  taken  from  this  same-storehouse,  —  from  this 
fluid  that  runs  in  the  blood-vessels  of  the  animal  body. 

239.  The  blood  is  not  flesh^nor  does  it  exhibit  any  resem- 
blance to  flesh.     It  is  a  homogeneous  fluid,  the  same  in  all 
the  arteries,  wherever  they  may  be  situated.     The  blood  that 
flows  -in  the  brain  is  of  the  same^nature  and  composition  as 
that  which  flows  in  the  bones  and  muscles.     The  blood  is 
not  a  simple,  but  a  compound  fluid.     It  contains  various  ele- 
ments, and  these  are  the  same  as  those  which  compose  the 
flesh.     These  simple  elements  are  principally  carbon,  oxygen, 
hydrogen,  and  nitrogen.     There  are.  others,  such  as  the  lime, 
that  enters  the  bones,  some  phosphorus  and  sulphur,  that  are 
found  in  the  hair,  the  nails,  and  the  brain.     These  are  the 
most  common    elements   in  nature.     Oxygen    and.  nitrogen 
compose  the  air ;  oxygen  and  hydrogen  form  water.     Carbon 


NUTRITION.  Ill 

is  the  principal  ingredient  in  charcoal  ;  it  is  the  predomi- 
nant element  in  vegetable  substances. 

240.  All  these  elements  are  found  in  the  blood.     But  they 
are   not    all    found    in   every     tissue     of  the   animal    body. 
There  is  no  lime  in   the  brain,   no  sulphur  in  the  muscles, 
and  no  nitrogen  in  the  fat.     Yet,  with  few  exceptions,  all  the 
various  parts  and  organs  are  mainly  composed  of  the  same 
elementary  atoms  —  carbon,   oxygen,  hydrogen,   and    nitro- 
gen.    The  difference  of  these  organs  is  owing,  not  to  the 
difference  of  their  component"  elements,  but  to  their  different 
combination  or  arrangement.     Combined  in  one  proportion, 
they   form    tendon ;     in    another,    they    form    muscle ;    in 
another,  potato,  tea,  coffee.     The  same  elements  in  various 
proportions,  and  with  some  ashes,  form  flesh,  peas,  beans, 
oats ;  and,  with  some  sulphur,  they  form*  hair,  bone,  nails, 
and  cheese.     The  blood  is  the  grand  storehouse  which  sup- 
plies all  these,  in  their  due  proportion,  to  every  organ  and 
texture. 

241.  The  arteries  carry  this,  blood  to  all  the  parts  of  the 
body ;    every   point,    however    minute,    receives   its   supply 
through  these  tubes.     The  transformation  of  the  blood  into 
flesh,  or  the  separation  of  such  elements  from  this  fluid  as 
will  compose  the  kind  of  flesh  that  is  needed,  is  done  in  the 
minute  extremities  of  the  arteries,  or  the  capillaries,  which 
stand  between  the  arteries  and  the  veins.     This  work  of  nu- 
trition  is  done  with  unerring   precision  in  health ;  just  the 
requisite  proportions  of  carbon,  oxygen,  and  hydrogen,  and 
of  the  other  elements,  are  measured  out ;  and  flesh  of  the 
proper  kinds  is  formed,  each  in  jts  appropriate  place ;  and 
thus  the  body  increas.es  in  size  and  stature. 

242.  All  additions  to  the  weight  of  the  body,  the  growth 
during  early  years,  and  the  increase  of  flesh  at  any  time, 
create  a  certain  demand  upon  the  blood  for  nutrition ;  but 
the  changes  of  particles,  during  the  whole  of  life,   create 
a   much    greater    demand   upon  the  blood  for  new    atoms. 
After  we  have  reached  our  fulness  of  staturev  in  ordinary 
health,  we  eat  and  drink  three  to  four  or  more  pounds  of 


112  PHYSIOLOGY    AND    HEALTH. 

solid  and  liquid  matter  a  day  ;  and  yet  our  weight  does  not 
usually  increase.  Even  after  making  this  daily  addition  for 
successive  years,  we  weigh  about  the  same  at  sixty  as  we  did 
at  twenty.  This  food  is  digested  and  converted  entirely,  or 
in  part,  into  blood ;  and  this  blood  is  converted-  into  flesh, 
muscle,  fat,  nerve,  &c. ;  arid  yet  these  organs^  and  parts 
remain  of  the  same  size. 

243.  The  diligent  arteries  are  almost  incessantly  adding 
atom  after  atom  to  these  organs,  and  yei:  do  not  enlarge 
them.     The  object  of  their  work  is, -not  merely  to  make  new 
atoms  of  flesh,  but  to  make  those  which  will  supply  the  place 
of  other  atoms,  which  have  served  their  purpose  in  the  living 
body,   and  have  been   carried    away.     It  has  already    been 
stated  (§  1,  p.  9)  that  however  long  the  body,  as  a  whole, 
may  continue  to  live,  none  of  its  component  particles  can 
enjoy  any  considerable  duration  of  life.     These  particles  are 
deposited,  by  the  arteries  or  the  capillaries,  in  the  various 
organs  and   tissues  ;  and  then  they  are  endowed  with  life, 
and  the  peculiar  properties  of  the  part  in  which  they  arc 
placed.     In  the  muscle,  they  have  the  power  of  contraction, 
and  in  the  brain,  the  power  of  feeling  and  perception;  and  in 
the   bone,    they   are    hard    and   strong,  and    apparently  in- 
sensible. 

244.  But  in  a  little  while  this  vitality,  this  property  of 
life,  is  exhausted,  and  the  atom  is  dead^    Then  it  is  removed, 
and  another  atom  takes  its  place,  to  go  through  the  same 
course  of  life,  action,  and  death.     This  succession  of  parti- 
cles, this  change  from  life  to  death,  and  this  renewal  of  life, 
are  constant,  and  almost  universal,  in  the  animal  body.     We 
are  dying,  atom  after  atom,  daily,  hourly,  momently  ;   and 
we  are  renewed  and  revived  in  the  same  degree,  and  at  the 
same  time.     We  enjoy,  therefore,  a  constant  freshness  of 
life.     This  is  the  united  work  of  the  arteries,  which  bring 
the  new  and  living  atoms,  and  of  the  veins  and  absorbents^ 
which  carry  the  old  and  dead  atoms  away.     The   arteries 
and  veins  have  already  been  described.     The  absorbent  ves- 
sels seem  to  be  spread  throughout  all  the  tissues.      Wherever 


NUTKITION.  113 

there  is  a  minute  artery  to  deposit  a  living  atom,  there  is 
an  absorbent  ready  to  carry  it  away  when  it  shall  have  fin- 
ished its  life  and  died. 

245.  Dr.  Edward  Johnson,  in  his  interesting  letters  on 
"Life,  Health,  and  Disease,"  thus  graphically  describes 
these  vessels :  "  There  is  arising  from  every  point  of  your 
body  a  countless  number  of  little  vessels,  actively  engaged  in 
the  pleasant  task  of  eating  you  up.  They  may  be  compared 
to  a  swarming  host  of  long,  delicate,  and  slender  leeches, 
attached,  by  their  innumerable  mouths,  to  every  point  of 
your  fabric,  and  having  their  bodies  gradually  and  progres- 
sively united  together,  until  they  all  terminate  in  one  tail, 
which  tail  perforates  the  side  of  one  of  the  veins  at  the 
bottom  of  the  neck,  on  the  left  side;  so  that  whatever  is 
taken  in  at  their  mouths  is  all  emptied,  ^by  the  other  ex- 
tremity, into  that  vein,  where  it  becomes  mixed  with  the 
blood." 


CHAPTER    V. 

Action  of  the  Nutrients  and  Absorbents.  —  Feeding  Sheep  on  Mad- 
der colors  Bones.  —  Balance  of  Nutrition  and  Absorption. —  In 
Youth,  Nutrition,  and  in  Old  Age,  Absorption  prevails.  —  Both 
more  active  in  the  Laborer.  —  Laborer  should  eat  more  Food. — 
Parts  that  are  used  more' nourished.  —  Wens  and  Swellings. — 
Produced  by  excessive  Action  of  Arteries,  and  removed  by  greater 
Action  of  Absorbents. 

246.  THE  arteries*  bring  the  blood,  and  deposit  the  new 
particles  of  flesh,  while  the  veins  and  absorbents  take  and 
carry  away  the  old  particles.  These  two  sjstems  are  con- 
stantly at  work,  antagonizing  each,  other.  One  set  pulls 
down  the  old  fabric,  taking  i|  away  atom  by  atom ;  at  the 
same  time,  the  other  set  rebuilds  the'  fabrip  anew,  and 
replaces  the  old  and  the  dead  with  new  and  living  portions. 
In  this  manner,  we  are  undergoing  a  perpetual  change; 
and  we  are  not  precisely  the  same  to-day  as  we  were 
10* 


114  PHYSIOLOGY    AND    HEALTH. 

yesterday.    Perhaps  we  have  not  now  an  atom  of  the  flesh 
that  we  had  ten  years  ago. 

247.  Though  the  individual  atoms  change,  the  whole,  the 
totality,  remains  unchanged.     The  new  atoms  have  the  same 
character,  the  same  sympathies,  and  perform  the  same  func- 
tions, as  those  that  went  before  them.     The  animal  body,  in 
this  respect,  is  like  a  community,  or  a  town  of  a  definite 
number  of  people.     The  individual  members  of  this  commu- 
nity are  continually  changing;  some  go  out  to  other  towns  — 
some  die;  but  their   places  are  filled  by  others  that  come 
from  abroad,  and  by  some  that  are  born.     The  individuals 
are  not  all  the  same  from  year  to  year ;    and,  in  course  of  a 
single  generation,  they  are  all  exchanged ;  and  yet  the  body, 
the  town,  remains   unchanged.     The   same    character    and 
habits   are  there,  the   same  principles  govern  them.     The 
community  is,  in  fact,  the  same,  even  after  every  one  of  its 
original  component  elements  has  been  removed  and  replaced 
by  others. 

248.  The  experiment  has  been  tried  of  feeding  pigs  and 
sheep    upon    madder,    which   is    a  pink   coloring    matter. 
When  some  of  these  animals  were  killed,  while  they  were 
living  upon  this  food,  the  bones  were  found  to  be  tinged  with 
red.     But  some  others  were  kept,  for  the  same  time,  upon 
madder,  and  afterwards  were  fed,  for  a  period,  with  hay  and 
grain ;  then  being  killed,  their  bones  were  found  to  be  as 
white  as  those  of  animals  which  had  never  eaten  madder. 
There  is  no  doubt  that  the  bones  of  these  last  animals  had 
been  stained  with  the  madder  while  they  lived  upon  it,  and 
that  they  became  white  when  they  again  were  fed  on  other 
food. 

249.  This  is  easily  explained  by  the  action  of  their  nutri- 
ent   and    absorbent   systems.     The    coloring  matter  of  the 
madder  was  carried  in  the  chyle  to  the  blood,  and  in  the 
blood  to  the  bone,  and  there  deposited ;    and,  when  this  is 
absorbed,  more  red  matter  is  brought  and  left  there;  and  this 
continues  as  long  as  madder  is  eaten.     But,  when  the  food  is 
changed,  no  more  red  matter  is  carried  to  the  bones,  and 


NUTRITION  .^  115 

that  which  was  there  is  taken   away,  and  its  place  is  sup- 
plied with  white  material. 

250.  During  the  middle  periods  of  life,  these  two  sets  of 
vessels   are   equally  active,  and   usually  perform    a  similar 
amount  of  work.     The  arteries  carry  and  deposit  as  many 
atoms  in  the  flesh  as  the  veins  and  absorbents  carry   away. 
The  one  builds  up  as  fast  as  the  other  pulls  down ;  so  that, 
though  some  pounds  are  added  daily  to  the  body,  it  does  not 
gain  in  weight ;  neither  does  it  lose,  though  as  much  is  car- 
ried away.     But  this  is  not  the  case  at  all  the  periods  of  life, 
nor  in  every  condition  of  health. 

251.  During  the   period   of  youth,  and  the  time  of  in- 
creasing flesh,  nutrition  predominates ;  more  atoms  are  then 
brought  in  the  arteries,  and  deposited,  than  are  taken  away 
by  the  absorbents.     When  the  body  is  wasting,  absorption 
predominates,  and  carries  off  more  than  the  arteries  deposit. 
When  we  grow  fat,  nutrition  is  the  more  active;  but  when 
we  grow  lean,  absorption  prevails.     The  whole  of  the  move- 
ments  of    life    are    more  rapid    in    the  earlier    years,    and 
slower  in  old  age,  than  in  the  middle  periods  of  life.     The 
heart  beats  quicker,  the  flow  of  blood  is  more  abundant,  and 
both  nutrition  and  absorption  are  more  rapid  in  the  former, 
and  slower  in  the  latter  period. 

252.  Liebig   supposes   that   every  action  of  any  of  the 
parts  of  the  body  is  attended  with  change  of  particles ;  that 
when  a  finger  moves,  some  of  the  atoms  in  the  muscle  that 
produces  the  motion  die  and  leave  their  places,  and  are  re- 
placed by  others.     When  we  move  the  arm,  the  legs,  or  use 
the  muscles  of  any  other  part  of  the  body,  the  same  changes 
take  place  in  the  muscular   atoms.     All    exercise  increases 
the  activity  of  both  the  nutrition  and  absorption.     In  order 
to  meet  the  increased  demands  for  new  flesh  to  supply  this 
waste  during  exercise,  the  heart  beats  quicker  —  more  blood 
is  carried  to  the  moving  parts ;  and  thus  more  new  flesh  is 
formed,  as  long  as  more  is  absorbed.     Every  one  knows  that 
the   heart   beats  rapidly,   and   sometimes   almost  palpitates, 
while  we  run  or  otherwise  exercise  violently.     Those  who 


116  PHYSIOLOGY    AND    HEALTH. 

suffer  from  disease  of  heart  cannot  make  great  exertions,  be- 
cause the  heart  cannot  carry  the  blood  needed  to  supply  the 
greater  waste. 

253.  The  waste  of  the  old  atoms  of  flesh,  and  the  demand 
for  new,  being  increased  by  exercise,  of  course  more  blood 
is  then  consumed  to  supply  the  want  which  is  thus  created ; 
and,  consequently,  more  food  must  be  eaten  and  digested,  to 
supply   the   blood    with  the    new   chyle  sufficient  to  repair 
this  loss.     (§  127,  p.  61.)     The  laborer  must  therefore  eat 
more  than  the  indolent,  and  individuals  in  active  youth  need 
more  food  than  in  quiet  old  age.     But,  in  inactive  life,  the 
absorption  is  comparatively  little,   and  the  nutrition  and  the 
consumption  of  blood  are  equally  small ;    there    is  less  de- 
mand for  food,  and  a  corresponding  diminution  of  appetite. 
If  the  idle  disregards  this  law  of  his  nature,  and  eats  as  much 
as  the  laborious,  the  stomach  is  troubled  with  the  burden; 
and,  if  it  digests  and  converts  the  food  into  chyle,  the  blood- 
vessels are  overfilled  with  the  amount  of  blood  which  they 
cannot  use,  and  the  whole  frame  is  heavy  and  sluggish.     The 
apostle's    command  that;  "  if  any  would  not  work,  neither 
should  he  eat,"  which  was  given  as  a  moral  law,  is  equally 
binding  as  a  physical  law,  and  cannot  be  disobeyed  without 
suffering. 

254.  The  processes  of  destruction  and  creation  have  usu- 
ally the  same  comparative  activity  in  all  parts  of  the  body,  so 
that  no  part  grows  fat  or  lean  more  than  another.     But  this 
is  not  always  the  case.     If  one  organ  or  part  is  more  active 
than  the  others,  it  grows  more  than  they.     Thus  the  arms  of 
some   laborers,  and  the  legs  of  others,  grow  disproportion- 
ately  large,    because   they  are  more  used  than  their  other 
limbs.     But  parts  that  are  not  used  at  all  waste  away,  and 
are  often  withered.     The  arm  of  one  of  my   neighbors  was 
palsied  about  twenty  years  ago,  and  it  is  now  shrunken  to 
the  size  of  a  child's  arm;   the  unused  muscles  are  nearly 
absorbed. 

255.  Wens,  and  other  fleshy  tumors,  are  the  effect  of  the 
unnatural  activity  of  the  nutrient  vessels,  which  deposit 


NUTRITION.  117 

more  fatty  or  other  fleshy  atoms  in  the  part  affected,  than  the 
absorbents  take  away.  Physicians  are  often  asked  to  scatter 
these  tumors.  This  is  done  by  stimulating  the  absorbents  to 
a  still  greater  activity  than  the  arteries,  so  that  they  may 
carry  away  more  atoms  than  the  others  bring.  The  glands 
of  the  neck  in  scrofulous  persons  sometimes  swell,  and  after- 
wards the  swelling  disappears.  A  boil  often  appears  upon 
the  skin  with  a  prominent  and  painful  swelling ;  but,  without 
coming  to  a  head,  or  discharging  any  matter,  it  goes  away. 
In  both  these  cases,  the  tumor  is  produced  by  the  superior 
activity  of  the  arteries,  and  is  carried  away  by  the  greater 
action  of  the  absorbents. 


CHAPTER  VI. 

The  Young  have  fresh  and  new  Atoms  of  Flesh.  — The  Aged  have 
old  Atoms.  —  Flesh  of  the  Active  is  new;  and  of  the  Idle,  old. — 
Blood  and  Vessels  same  in  all  Parts. —  Vessels  select  Elements 
from  the  Blood,  in  due  Proportion,  to  form  the  various  Tissues.  — 
Unerring  Precision  of  Nutrition.  —  Difference  of  the  Blood  in  the 
Arteries  and  in  the  Veins. 

256.  THIS  double  work  of  nutrition  and  absorption,  pro- 
ducing changes  of  the  component  parts  of  the  body,  never 
ceases  from  the  beginning  to  the  end  of  life.     But  it  is  riot 
equally   rapid   in    all   periods,  nor  in  all    persons.     In    the 
earlier  years  of  childhood   and  youth,  all  the  processes  of 
animal  life  are  more  active,  and  the  particles  are  more  fre- 
quently changed  than  in  middle  life.     Consequently,    their 
flesh  at  these  periods  is  ever  new  and  young.     But  in  old 
men,  all  these  operations  are  more  sluggishly  and  feebly  car- 
ried  on.     Their  particles  are  not  frequently  changed,  and 
therefore  the  atoms  of  their  flesh  are   old,   as  well  as  their 
whole  bodies. 

257.  As  these  changes  are  frequent  in  the  active  and  in- 
dustrious, their  atoms  remain  but  a  short  time  in  the  living 
body,  before  they  are  taken  away.     This  gives  them  a  per- 


118  PHYSIOLOGY   AND    HEALTH. 

petual  freshness  of  youth  in  their  flesh;  they  are,  there- 
fore, lively  and  prompt  in  action.  These  changes  take  place 
more  slowly  in  the  inactive;  their  atoms  remain  a  longer 
time;  and  their  flesh  is  therefore  always  old,  and  indisposed 
to  action.  It  is  easy  to  see  this  difference  between  the  en- 
ergy and  sprightliness  of  one  who  has  always  accustomed 
himself  to  action  abroad,  and  the  heavy  sluggishness  of 
another,  who  has  lived  delicately,  and  avoided  exercise. 
Compared  with  his  years,  the  one  is  ever  young,  while  the 
other  is  ever  old. 

258.  We   have   no  means  of  knowing  how,  or  by  what 
means,  the  final  work  of  nutrition  is  done.     We  only  know 
the  instruments  with  which  it  is  accomplished,  and   the  ma- 
terials that  are  used.     Anatomists  have  examined  the  blood- 
vessels,   and   chemists   have    analyzed   the  blood,  and  have 
taught  us  the  shape  of  one  and  the  composition  of  the  other ; 
and  there  our  knowledge  stops.     We  cannot  penetrate  any 
farther  into  the  mysteries  of  nature.     So  far  as  the  eye  of 
man  can  discover,  the  blood-vessels  are  the  same  in  structure 
and  character,  in   all  the  prgans  and    tissues   of  the  body, 
and  the  same  blood  is  found  in  all.     And  yet,  with  a  wonder- 
ful precision,  these  little  nutrient  vessels  select  out  of  this 
common  storehouse  of  nutriment  just  those  elements,  and  in 
just  their  varied   proportions,  that  are  needed  to  form  the 
various  kinds  of  flesh  and  substance  that  compose  the  ani- 
mal body. 

259.  In  the  fat,  the  organs  of  nutrition  select  from  the 
blood  79  parts  of  carbon,  11£  parts  of  hydrogen,  and  9J- 
parts  of  oxygen ;  and  with  these  form  fatty  atoms.     In  the 
hair,  they  take  50  parts  of  carbon,  6  parts  of  hydrogen,  17 
parts  of  nitrogen,  and  26  parts  of  oxygen  and  sulphur,  and 
make  an  atom  of  hair.     And  from  the  blood  in  the  muscle, 
they  take  51  parts  of  carbon,  7  parts  of  hydrogen,  15  parts 
of  nitrogen,  21  parts  of  oxygen,  and  4  parts  of  other  mat- 
ters, and  form  muscular  pai  deles.     In  a  similar  manner,  the 
vessels  of  the  brain  select  the  brain ;   and  in  the  skin,  and 
in  all  other  organs,  they  select  the  very  kinds  and  proportions 


NUTRITION.  119 

of  the  elements  that  compose  each,  and  no  other.  They 
take  just  enough  of  each  element,  neither  more  nor  less,  and 
combine  them  in  the  due  proportion  of  each  kind,  to  form 
the  part  which  is  wanted. 

260.  Although  the  different   tissues  of  the  animal  body 
are  so  nearly  alike  in  their  composition,  and  so  slight  a  vari- 
ation would  produce  another  kind  of  flesh,  yet,  in  health,  no 
mistake  is  made.     Each  organ  and    tissue  receives  flesh  of 
its  own  kind.     Muscle  is  not  deposited  in  the  brain,  nor  bone 
in  the  muscle,  nor  tendon  in  the  liver.     In  every  part,  the 
blood-vessels  act  with  such  unvarying  and  beautiful  precision, 
and  perform  their  work  with  such  faithfulness  to  their  pur- 
pose, that  they  might   almost  seem  to  be   endowed  with   a 
special  intelligence,  if  we  were  not  assured  that  they,  even 
the  minutest  of  them,  are  under  the  coiistant.^supervision  and 
direction  of  that  paternal  Providence,  without  whose  notice 
not  an  atom  moves  nor  a  sparrow  falls  to  the  ground. 

261.  Thus  all  the  atoms  of  flesh,  all  the  parts  of  the  ani- 
mal body,  were  first  in  the  stomach,  and  next  in  the  arteries ; 
and  then  they  became  living  flesh,  and  acted  a  while,  and  died. 
Then,  again,  all  these,  with  the  exception  of  the  hair,  the 
nails,  and  the  outer  skin,  which  grow  out  and  fall,  are  once 
more  taken  into  the  vessels,  and  are  found  in  the  veins. 
The  blood  in  the  arteries  differs  from  that  in  the  veins,  in  its 
nature  and  its  composition.     In  one,  it  is  scarlet,  rich,  nutri- 
tious, loaded  with  new  particles  of  digested    food,   and   is 
therefore  capable  of  giving  life  and  strength  to  any  of  the 
tissues.       In  the  other,  it  is  dark  purple;  it  h:is  lost  its  rich 
particles,  and  is  therefore  innutritions ;  it  is  also  loaded  with 
the  dead  and  wasted  particles  that  have  lived  and  died  in  the 
body.     If  the  venous  blood  be  thrown  into  the  arteries,  and 
circulated  through  the  system,  it  not  only  must  fail  to  nourish 
and  give  new  particles  of  flesh  to  the  tissues,  but,  with  its 
wasted  and  offensive  burden,  it  must  carry  disease  01   death 
to  the  body. 

262.  The  veins  are  incessantly  receiving  additions  of  the 
particles  of  the  exhausted  flesh,  and  would  soon  be  so  over- 


120  PHYSIOLOGY    AND    HEALTH. 

loaded  as  to  be  incapable  of  action,  if  there  were  not  some 
means  provided  to  carry  these  out  of  the  body.  This  might 
seem  a  difficult  matter.  These  dead  atoms  are  in  the  veins, 
and  those  are  buried  in  the  deepest  recesses  of  the  body, 
apparently  beyond  the  reach  of  any  external  influence,  arid 
without  any  outlet  to  the  world  abroad.  But  Nature  has  no 
difficulties.  Her  means  are  always  adequate  to  her  wants. 
Her  process  of  relieving  the  living  body  of  those  useless  and 
burdensome  matters  is  made  simple  and  easy,  by  means  of 
the  lungs  and  respiration,  and  of  the  skin  and  perspiration. 


PART    III. 
RESPIRATION. 


CHAPTER   I. 

Wasted  Particles  carried  out  of  the  Body. —  Composition  of  Blood  in 
right  Side  of  the  Heart.  —  Lungs  protected  by  Bones  of  Chest.  — 
Spine.  —  Breast-Bone.  —  Ribs.  —  Position  of  Ribs. 

263.  THE  wasted  particles  of  the  animal  body — those  that 
have  lived  and  have  been  a  part  of  the  living  system  —  have 
been  rejnoved  from  their  places  in  the  various  organs,  and 
carried  into  the  veins,  and  through  them  to  the  right  side 
of  the  heart.     As   nutrition  and  absorption  are  continually 
going  on  in  the  body,  these  old  particles  must  accumulate  in 
the  veins  and  heart ;  and,  as  they  amount  to  several  ounces  a 
day,  they  would  soon  overload  and  destroy  the  living  system, 
if  they  were  not  carried  out  from  it.     This  is  done;  and 
they  find   an  outlet  through  the  lungs  as  fast  as  they  are 
removed  from  their  original  places  of  life  and  action  in  the 
various  tissues. 

264.  The  venous  blood  —  that  which  is  gathered  in  the 


RESPIRATION. 


121 


right  side  of  the  heart,  from  all  the  various  parts  of  the  body  — 
consists  of  three  kinds  of  materials  :  1st,  the  residue  of  the 
arterial  blood  after  nourishing  the  body,  or  that  which  is  left 
after  the  particles  have  been  selected  for  the  nourishment  of 
the  textures;  2d,  the  old  and  dead  atoms  of  flesh;  and, 
3d,  the  chyle,  or  digested  food  brought  through  the  lacteals. 
Neither  of  these  three  elements  can  nourish  the  body  The 
remnant  of  the  arterial  blood  has  lost  much,  if  not  all,  of  its 
life-giving  qualities.  The  dead  particles  would  be  poisonous 
if  carried  round  again;  and  the  new  chyle  is  not  yet  pre- 
pared to  furnish  nutriment.  They  must,  therefore,  all  be  sub- 
mitted to  some  process  by  which  the  first  shall  be  strength- 
ened, the  second  carried  out  of  the  body,  and  the  third 
perfected,  before  this  blood  can  be  used  again  to  nourish  the 
body.  All  this  is  done  by  means  of  the  air*in  the  lungs. 

265.  The  lungs  of  man  are  placed  within  the  chest, 
at  the  upper  part  of  the  trunk.  They  are  organs  of  ex- 
ceeding delicacy  in  their  FIG.  XV.  Bones  of  th*  Cheat. 
structure,  and  would  not 
bear  with  impunity  any 
exposure  to  external  in- 
jury. They  are  therefore 
protected  with  great  care. 
They  are  covered  on  all 
sides  with  a  bony  frame- 
work, which  prevents  all 
contact  with  external  ob- 
jects. The  bones  which 
compose  the  walls  of  this 
chest  are  so  arranged,  and 
fixed  with  joints  and  mus- 
cles, that  they  admit  of 
very  free  motion,  and  al- 
low to  the  internal  cavity 
great  range  of  expansion 

and    contraction,   for    ad-      Q  Breast -bone.     bt  b.  Back-bone, 
mitting  and  expelling  air.  c,  c,  c,  c.  Ribs. 

n 


122  PHYSIOLOGY    AND    HEALTH. 

266.  The  chest  (Fig. XV.)  extends  from  the  neck  to  the  ab- 
domen.    It  is  conical  in  shape,  being  small  at  its  upper  end, 
and  larger  at  the  lower  part.     Jt  is  enclosed  by  bone  at  the  top 
and  on  its  sides,  and  by  muscle  at  the  bottom.     The  breast- 
bone,'.a,  (Fig.  XV.  p.  121,)  is  in  front;    the  spine,  b.  b,  or 
back-bone,  is  behind ;  and  the  ribs,  c,  c,  c,  cover  the  sides  of 
the  chest. 

267.  The  spine,  or  back-bone,  is  composed  of  twenty-four 
bones,  called  vertebra,  which  are  connected  by  thick  layers 
of  very  strong  and  elastic  cartilage,  or  gristle,  between  them. 
These  give  to  the  column  great  flexibility  and  freedom   of 
motion,  and  such  strength  that,  through  all  the  chances  of 
accidents  and  violence,  these  bones  are  very  rarely  broken  or 
displaced.     Yet  it  may  be  bent  in  any  direction,  and  is  capable 
of  sustaining  great  burdens  that  may  be  placed  upon  the  head. 
Twelve  of  these  bones  form  part  of  the  chest,  and  to  these 
twelve  vertebrae  or  bones  of  the  back  are  attached  twenty-four 
ribs,  twelve  on  each  side. 

268.  The  breast-bone,  a,  is  thin  and  flat,  reaching  from  the 
neck  to  the  region  of  the  stomach.     It  is  covered  with  so  little 
flesh  as  to  be  perceptible  to  the  touch.     At  the  lower  end  is 
attached  a  cartilage  or  gristly  substance,  that  extends  about 
two  or  two  and  a  half  inches  downward,  and  ends  in  a  point 
at  the  pit  of  the  stomach.     This  breast-bone  forms  the  front 
pillar  of  the  chest,  though  by  no  means  an  immovable  one,  for 
it  rises  and  falls  with  all  the  motions  of  the  ribs. 

269.  The  ribs,  c,  c,  c,  compose  the  principal  part  of  the 
framework  of  the  chest.     They  surround  the  cavity  from  the 
back  to  the  breast-bone,  covering  all  the  sides  and  most  of 
the  anterior  and  posterior  portions  of  the  cavity.      All  are 
joined  to  the  back-bone  by  their  posterior  end,  and  ten  of 
them  are   connected  with   the  breastrbone  by  their  anterior 
«nds.     Some  of  these  are  fixed  directly  to  the  breast-bone; 
others  terminate  in  cartilages  of  an  inch  or  more  in  length, 
that  extend  to  the  breast-bone  ;  by  which  arrangement  these 
ribs  have  a  great  freedom  of  motion. 

270.  The  ribs   nearly   surround   the  cjiest,  somewhat   as 


RESPIRATION.  123 

hoops  surround  a  barrel.  But  their  course  is  not  horizontal. 
They  incline  downward  from  the  back-bone  to  the  breast- 
bone in  front ;  consequently,  the  diameter  of  the  chest  is  so 
much  lessened  by  this  obliquity  of  position ;  but  when  the 
ribs  are  raised  to  a  horizontal  position,  at  right  angles  with 
the  axis  of  the  chest,  this  diameter  is  increased,  and  the 
capacity  of  this  cavity  is  enlarged.  This  is  p 

easily  shown  by  the  experiment  of  putting 
a  large  hoop  obliquely  upon  a  barrel  of 
smaller  diameter.  The  hoop,  a,  c,  in  its  ob- 
lique position,  touches  the  barrel ;  but,  if  the 
hoop  be  raised  horizontally  to  6,  it  would  ex- 
tend beyond  the  cask,  and  allow  it  a  much 
greater  expansion. 


CHAPTER    II. 

Movements  of  Ribs —  Diaphragm.  —  Expansion  of  Chest  in  Inspira. 
tion.  —  Contraction  in  Expiration.  —  Size  of  expanded  and  con. 
tracted  Chest. 

271.  THE  posterior  ends  of  the  ribs  are  attached  to  the 
back-bone,  and  fixed.     The  motions  are  all  made  with  the 
anterior  ends,  which  are  free.     They  are  joined  to  the  spine 
in  such  a  manner  that  they  can  only  move  upward  and  down- 
ward, not  from  side  to  side.     The  spine  being  the  pillar 
upon  which  the  frame  of  the  chest  rests,  it  is  fixed  and  im- 
movable in  breathing ;  but  all  the  movements  of  the  ribs  and 
breast-bone  are  made  upon  it.     These  are  lifted  up  and  fall 
down  at  every  respiration. 

272.  The  first  or  upper  rib  is  fixed  and  motionless ;  the 
second  has  very  little  motion;    the  third  has  more  motion 
than  the  second ;  and  the  fourth  more  than  the  third.     This 
motion  goes  on  increasing  to  the  eleventh  and  twelfth,  which 
move  very  freely.     There  are  several  muscles  which  are  at- 


124  PHYSIOLOGY    AND    HEALTH. 

tached  to  the  back-bone  and  to  the  ribs,  and  fill  all  the 
spaces  between  them.  Some  of  these  are  attached  by  one 
end  to  the  spine,  and,  running  obliquely  forward  and  down- 
ward, are  attached  by  the  other  end  to  the  ribs  below. 
Others  are  attached  by  one  end  to  one  rib  above,  and  by 
the  other  end  to  another  rib  below.  When  these  muscles 
contract,  they  lift  the  ribs.  The  posterior  end  of  each  rib 
rolls  in  its  socket  in  the  spine;  but  the  main  portion  of  the 
bone  is  raised  and  carried  outward,  and  the  whole  cavity  of 
the  chest  is  then  expanded,  in  the  same  manner  as  the  hoop 
(Fig.  XVI. a,  c,)  would  allow  the  cavity  of  the  cask  to  be  ex- 
panded, if  the  side  c  were  lifted  to  the  level  of  the  side  a, 
which  is  supposed  to  be  fixed. 

273.  The  ribs,  spine,  breast-bone,  arid  muscles  (Fig.  XV. 
p.  121)  bound  the  chest  on  all  its  sides.     As  this  cavity  is 
conical,  there  is  hardly  any  surface  at  the  top.     But  there  is 
a  broad  and  extensive  surface  at  the  bottom  of  the  cone, 
which  is  covered  by  a  flat  muscle,  called  the  diaphragm. 
(Fig.   II.  £?,  p.   19.)      This  performs  a  part  of  the  greatest 
importance  in   the  work    of  respiration.     It  is  the  flexible 
partition  that  divides  the  chest  from  the  abdomen,  and  sep- 
arates the  respiratory  from  the  digestive  organs.     Its  edges 
are  attached  to  the  back-bone,  and  to  the  lower  edge  of  the 
lower  ribs,  to  the  breast-bone,  and  to  all  the  lower  part  of 
the  chest.     It   forms  an    arch,   upon  the    upper   or  convex 
surface  of  which  the  lungs  rest;  and  in  the  hollow   below 
some  of  the  organs  of  the   abdomen  —  the  liver,  stomach, 
&c. —  are  placed. 

274.  When  the  diaphragm  is  at  rest,  its  arch  points  upward 
into  the  chest,  as  the  bottom  of  a  common  glass  bottle  is 
turned  into  its  cavity ;  and  its  upper  point  reaches  as  high  as 
the  fourth  rib,  and,  consequently,  must  very  materially  lessen 
the  capacity  of  the  chest,  and  press  upon  the  lungs.     But 
when  it  is  in  action  and  contracted,  the  arch  is  drawn  down, 
and,  leaving  a  space  behind,  enlarges  the  capacity  of  the 
chest,  and  allows  more  room  for  the  lungs  to  expand.     The 
diaphragm  is  the  dividing-wall  between  the  lungs  and  diges- 


RESPIRATION.  125 

tive  apparatus.  (Fig.  V.<7,  p.  19.)  The  lungs  lie  in  contact 
with  it  above,  (Fig.  V.  a,  6,  p.  19,)  and  the  digestive  appa- 
ratus lies  in  contact  with  it  below.  (Fig.  V.  e,  /,  p.  19.) 
When  it  is  expanded,  it  rises  into  the  chest,  and  the  lungs  are 
pressed  up,  and  the  abdominal  organs  follow  immediately 
behind.  And,  on  the  other  hand,  when  it  contracts  and 
lessens  the  arch  to  give  expansion  to  the  lungs,  it  must 
press  the  abdomen  and  its  contents  downward  and  out- 
ward. A  simple  and  easy  illustration  of  the  operation 
of  the  diaphragm  in  breathing,  may  be  found  in  the  com- 
mon India-rubber  bottle.  If  we  hold  this  in  one  hand 
and  press  the  bottom  inward  with  the  finger,  the  air  is 
forced  out  through  the  neck.  If,  then,  we  remove  the  fin- 
ger, the  bottom  returns  to  its  natural  position,  and  then  the 
air  flows  through  the  neck  to  fill  the  increased  cavity. 

275.  By  these  two  combined  actions  of  the  muscles  of  the 
ribs  and  of  the  diaphragm,  the  chest  is  enlarged.     The  mus- 
cles on  the  sides  of  the  chest  raise  the  ribs,  and  extend  their 
circle  forward  and  outward.     The  diaphragm  draws  down 
its  arch  from  the  fourth  to  below  the  seventh  rib,  and  thus 
enlarges  the  chest;   and  the  lungs  having  room  for  expan- 
sion, the  air  is  pressed  into  them  to  fill  the  vacuum  left  by 
the  enlarging  chest.     This  is  the  mechanical  part  of  the  pro- 
cess of  inspiration. 

276.  After  the   chest  is  thus  sufficiently  expanded,  the 
muscles  of  the  ribs  and  the  diaphragm  relax  and  lose  their 
firmness.     Then  the  action  of  other  muscles,  aided  by  the 
elasticity  of  the  cartilages,  carries  the  ribs  downward ;  and,  in 
going  down,  they  lessen  the  diameter,  and  consequently  the 
capacity  of  the  chest,  by  bringing  the  sides  nearer  to  each 
other,  and  the  breast-bone  nearer  to  the  back-bone.     At  the 
same  time,  -the  muscles  that  cover  the  abdomen   press  upon 
its  contents,  and  force  them  against  the  diaphragm.     This 
yields  to  the  pressure,  and  rises  upward  and  presses  upon  the 
lungs,  which  retreat  before  it,  and  the  air  is  expelled.     This 
is  the  process  of  expiration. 

277.  Fig.  XVII.  represents  an  outline  of  the  front  view  of 

11* 


126 


PHYSIOLOGY    AND    HEALTH. 


the  expanded  and  contracted  chest.  The  full  lines  d,  dt  d, 
show  the  size  of  the  cavity  when  the  ribs  are  drawn  down 
and  the  diaphragm  is  expanded  upward.  The  dotted  lines 

J? 'IG.  XVII.  Outline  of  the  Expanded  and  Contracted  Chest. 
Front  View. 


a.  Neck. 

b,b,b,b,b,b. 
panded  chest. 


Size  of  the  ex- 


c,  c,  c.     Position    of  tBe 
phragm  when  drawn  down. 


dia- 


d,d,d,d,d,d. 
tracted  chest. 


Size  of  the  con- 


e,  e,  e.      Position   of   the  dia- 
phragm when  expanded. 


show  its  size  when  the  ribs  are  lifted  and  the  diaphragm 
drawn  down.  When  the  ribs  are  at  rest,  they  lie  downward 
and  inward,  and  their  surface  is  represented  by  the  lines 
d,  d,  d,  d,  d,  d;  but,  when  they  are  raised,  they  are  carried  out- 
ward, and  their  surface  is  represented  by  the  dotted  lines 
b,  b,  b,  b,  b,  b.  When  the  diaphragm  is  at  rest,  it  projects 
upward-  in  form  of  the  line  e,  e,  e ;  but,  when  it  is  in  ac- 
tion, it  is  drawn  downward  in  form  of  the  line  c,  c,  c. 
The  upper  point  e  reaches  as  high  as  the  fourth  rib.  The 
upper  point  c  reaches  as  high  as  the  seventh  rib.  It  is  now 
very  plain  that  the  cavity  6,  6,  b,  c,  c,  c,  b,  b,  6,  is  larger  than 
the  cavity  d,  d,  d,  e,  e,  e,  d,  d,  d,  and  the  difference  in  size 
must  be  in  proportion  to  the  extent  of  the  motions  of  the  ribs 
and  the  diaphragm. 


RESPIRATION. 


127 


CHAPTER   III. 

Lun  TS.  —  Situation.  —  Tissues.  —  Windpipe  —  Glottis.  —  Organ  oi 
Voice.  —  Air-Tubes  and  Cells.  —  Mucous  Membrane.  —  Coughing. 

—  Interweaving  of  Air-Vessels  and  Blood- Vessels.  —  Inspiration 

—  Expiration.  —  Respiration.  —  Cooperation  of  Parts. 

278.  THE  lungs  are  situated  within  the  chest,  which  has 
been  now  described.  There  are  two  lungs,  (Pig.  XVHI. 
a,  &,)  placed  one  on  the  right,  and  the  other  on  the  left  side 
of  the  chest.  The  heart  lies  between  them,  (Fig.  XVIII.  d,) 
and  these  completely  fill  this  cavity.  (Fig.  V.  a,  6,  c.)  The 
lungs  are  very  soft  and  spongy.  They  contain  little  or  no 
flesh,  but  are  composed  almost  exclusively  of  tubes  and  cells, 
which  are  to  be  filled,  some  with  blood,,  and*  others  with  air. 

FIG.  XVIH.   Lungs  and  Heart. 

c ' 


a,  Left  lung. 
6,  Right  lung. 

c,  Windpipe. 

d,  Heart. 

e,  Great  artery 
carrying  blood  to 
lungs. 

f,  Great  vein. 
ff,  Great  artery 

carrying  blood  to 
the  body. 


279.  The  air-tubes  begin  at  the  back  part  of  the  mouth 
and  nostrils  with  a  single  cylinder,  which  leads  through  the 
neck  to  the  chest;  but  in  the  lungs  they  are  divided  and  sub- 
divided into  smaller  arid  smaller  tubes,  which  are  distrib- 


128  PHYSIOLOGY   AND   HEALTH. 

uted  throughout  the  whole  respiratory  organs.  The  blood- 
vessels (§  225,  p.  103)  proceed  from  the  heart  in  large  trunks, 
and,  like  the  air-tubes,  are  divided  and  multiplied  until  they 
terminate  in  minute  branches  of  imperceptible  size,  which 
lie  in  contact  with,  and  spread  over,  the  air-cells.  Then 
these  little  blood-vessels  are  again  gathered  together  into 
larger  and  larger  tubes,  until,  at  last,  they  form  two  large 
trunks,  that  enter  the  heart.  These  trunks  are  of  the  same 
size  as  those  which  left  the  heart  to  carry  the  blood  to  the 
lungs. 

280.  The  windpipe,  or  trachea,  is  composed  of  somewhat 
stiff  rings  of  cartilage  or  gristle,  so  that  it  is  easily  felt  in 
the  front  of  the  throat.     The  upper  end  of  this  tube  is  usu- 
ally  open;  but  the  epiglottis    (§§  20,   21,    22,   p.    16)    is 
placed  there  to  cover  over  and  protect  this  passage  when- 
ever the  food  passes  over  it,  on  its  way  from  the  tongue  to 
the   oesophagus.     But,  when    we   are   not   swallowing,  this 
valve  stands  open. 

281.  The  upper  end  of  the  windpipe  opens  into  the  back 
chamber  of  the  mouth,  by- a  narrow  chink,  called  the  glottis 
This  is  made  by  the  approximation  of  the  two  sides  of  the 
tube,  so  that  the  air  may  produce  sounds  when  it  passes  be- 
tween  them.     Some  muscles,  which  are  attached  to  these 
sides,  draw  them   more   closely  together,  or   allow  them  to 
separate.     By  thus  opening    or    narrowing  this    chink,  the 
sounds  which  are  made  by  the  air  passing  through  it,  are  va- 
ried.    -This  is  the  organ  of  voice  ;  and  these  sounds  are  the 
various  tones  which  we  utter  in  language,  in  singing,  or  in 
crying.     When    this  part  of  the  windpipe    is    diseased    by 
what  is  called,  a  cold  in  the  throat  or  otherwise,  these  tones 
are  changed,  and  often  destroyed.     A  man  then   loses  the 
control  of  his  voice,  and  can  neither  sing  nor  talk  as  he  does 
in  health.     Sometimes  the  voice  is  entirely  destroyed  or  sus- 
pended, and  then  the  sufferer  can  only  speak  with  the  mouth 
in  a  whisper.     A  gentleman,  whom  I  have  seen  while  writing 
this  chapter,  has  not  been  able  to  speak  a  loud  word  for  three 
months,  in  consequence  of  ulceration  about  the  glottis. 


RESPIRATION. 


129 


282.  At  the  junction  of  the  neck  with  the  chest,  and  just 
behind  the  top  of  the  breast-bone,  the  great  air-tube,  the 
windpipe,  is  divided  into  two  tubes,  or  bronchi.  One  of 
these  goes  to  the  right,  the  other  to  the  left  lung.  After 
entering  their  respective  lungs,  they  divide  into  smaller 
branches  or  tubes,  as  represented  in  Fig.  XIX.  These 

FIG.  XIX.     Windpipe  and  Air-  Vessels  of  the  Lungs. 


a.  Windpipe. 

b.  Left  lung. 

c.  Great  brancn  of  the  air-tube 
going  to  the  right  lung. 

rf,  d,  d.  Minute  branches  of  the 
air-tubes. 

e,  e.  Air-cells  at  the  minute 
termination  of  the  air-tubes,  mag- 
nified. 


tubes  do  not  divide  so  minutely  as  the  blood-vessels,  but  ter- 
minate somewhat  abruptly  in  a  great  number  of  minute  cells. 
(Fig.  XIX.  6,  e.)  These  cells  are  estimated  to  be  one  hun- 
dredth of  an  inch  in  diameter.  They  are  so  numerous  as  to 
be  distributed  to  every  part  of  the  lungs ;  and  the  extent  ot 
the  inner  surface  of  the  whole,  collectively,  is  estimated  vari- 
ously by  physiologists.  Some  suppose  it  to  be  20,000  square 
inches ;  others  thirty  times  the  whole  surface  of  the  body. 
But  all  agree  that  there  is  a  very  extensive  surface  presented 
to  the  action  of  the  air. 

283.    These  air-tubes  and  air-cells  are  lined  with  a  mucous 
membrane  of  exceeding  delicacy,  which,  during  the  whole  of 


1  PHYSIOLOGY    AND    HEALTH. 

life,  will  bear  the  presence  of  pure  air,  but  will  not  tolerate, 
for  a  single  moment,  the  presence  of  any  other  substance, 
not  even  a  drop  of  water,  as  most  of  us  have  had  occasion  to 
know  in  some  part  of  our  lives.  This  lining  is  thin  and 
sensitive,  and  very  liable  to  be  disordered.  Most  of  our 
colds  and  catarrhs  are  but  affections  of  this  membrane. 
And  our  coughs  are  mostly  caused  by  some  irritation  applied 
to  it,  or  derangement  in  it.  Whenever  it  is  not  in  a  com- 
fortable condition,  —  when  it  is  dry  for  want  of  mucus,  or 
covered  with  too  much  of  it,  —  or  when  any  particle  of  food, 
or  any  other  foreign  substance,  is  lodged  in  any  part  of  the 
air  passages  or  cells,  or  even  gets  within  the  glottis,  —  then 
nature  sets  up  a  violent  expulsory  effort  to  press  the  air  out 
suddenly,  and  to  blow  and  force  away  the  intruder,  or  relieve 
the  irritation.  This  is  coughing. 

284.  We  perceive  this  sometimes  when  we  breathe  dust, 
or  offensive  gases,  or  pungent  matters,  all  of  which  irritate 
and  offend  this  sensitive  texture.    But,  delicate  as  it  is,  it 
may,  by  use,  lose  its  sensibility,  and  become  accustomed  to 
bear  very  injurious  substances,  as  the  sole  of  the  barefoot 
boy  loses  its  delicacy,  and  will  bear  the  rough  surface  of  the 
street  without  suffering ;  and  as  the  hands  of  the  smith  and 
of  the  dyer  lose  much  of  their  sensitiveness  to  heat,  so  that 
they  can,  without  apparent  pain,  handle  iron  and  plunge  into 
dyes  so  hot  as  to  burn  others;  so  the  membrane  of  the  lungs 
becomes  used  even  to  tobacco-smoke,  and  bears  its  frequent 
and  almost  perpetual  presence,  without  appearing  to  suffer 
any  harm. 

285.  The  heart  is  placed  about  the  middle  of  the  chest, 
and  between  the  lobes  of  the  lungs,  (§205,)  (Fig.  XVIII. 
p.  127,)  and   sends   its    blood-vessels  to  the   right   and   to 
the  left,  through  each  of  these  lobes.     These  vessels  ramify 
through  every  part  of  the  organ,  and  are  interwoven  with  the 
air-tubes    (Fig.  XX.)   These  myriads  of  minute  arteries  come 
in  contact  with  the  air-cells,  and  are  separated  from  them 
only  by  an  exceedingly  thin  membrane,  so  thin  that  gasea 


RESPIRATION. 


can  pass  through  it  from  the  air-cells  to  (he  blood-vessels, 
and  from  the  blood-vessels  to  the  air-cells;  but  it  is  suffi- 
ciently thick  to  prevent  the  passage  of  fluids. 

FIG.  XX.  Interweaving  of  the  Air-tubes  and  Blood-vessels  in 
the  Lungs. 


a.  Windpipe. 

6,  c.   Right  and  left  lung. 

d.  Heart. 

€,  «.  Divisions  of  the  great  air- 
tubes  going  to  the  right  and  left 
lungs. 

/,  /.  Pulmonary  arteries  carry- 


ing the  blood  from  the  heart  to  tho 
lungs. 

g,  g.  Pulmonary  veins,  carrying 
the  blood  from  the  lungs  to  the 
heart. 

h.  h,  h,  h.  Air-cells  at  the  termi- 
nations of  the  air-tubes.  ^ 


286.  When  the  ribs  are  lifted  and  the  chest  expanded  at 
the  sides,  and  the  diameter  thereby  increased,  and  when  the 
diaphragm  is  drawn  down,  and  the  chest  enlarged  below, 
there  must  be  a  vacuum  within  this  cavity  to  be  supplied  by 
air.  The  only  passage  into  the  chest  is  through  the  mouth 
and  windpipe,  and  into  the  lungs;  consequently,  when  the 
cavity  of  the  chest  is  enlarged,  the  air  rushes  into  the  air- 


132  PHYSIOLOGY -AJSD    HEALTH. 

tubes,  and  fills  all  the  air-cells.  On  the  other  hand,  when 
the  ribs  fall,  and  the  abdominal  muscles  press  upon  the 
digestive  organs,  and  force  the  diaphragm  to  rise,  the  lungs 
are  compressed,  the  air  is  expelled,  and  the  air-cells  closed. 

287.  During  life,  there  is  a  constant  succession  of  these 
actions.     The  air  is  at  one  moment  drawn  into  the  lungs,  by 
the  contraction  of  the  diaphragm  and  the  lifting  of  the  ribs, 
and  at  the  next  moment  it  is  expelled,  by  the  falling  of  the 
ribs  and  the  contraction  of  the  abdominal  muscles.     These 
two  operations  constitute  what  is  caHed  respiration.     Each 
respiration  supplies  the  lungs  with  a  new  quantity  of  air. 

288.  This  is  the  operation  of  respiration.     All  the  parts 
of  its  apparatus,  —  the  framework  of  bone,  the  muscles  of  the 
ribs,  and  the  diaphragm,  —  all  cooperate  in  the  work,  and  are 
necessary  to  effect  its    purpose,    which  is  to  bring  the  air 
and  the  blood  together,  and  to  relieve  the  latter  of  its  impu- 
rities, and  fit  it  for  the  support  of  the  living  body. 


CHAPTER  IV. 

Waste    Particles.  —  Carbon.  —  Air,    Composition  of. — Oxygen 

Nitrogen. — Affinity  of  Oxygen  for  Carbon.  —  Carbonic  Acid. — 
Carbon  meets  Oxygen  in  the  Nutrient  Vessels.  —  Blood  absorbs 
Oxygen  from  the  Air,  and  gives  out  Carbonic  Acid. 

289.  THE  respiratory  apparatus  and  its  operation,  which 
carry  out  from  the  body  the  dead  and  waste  particles,  afford 
striking  evidences  of  Nature's  skill,  and  beautiful  illustra- 
tions  of   her   handiwork.     The  principal    elements  of  this 
waste  matter,  now  mixed  with  the  venous  blood,  are  carbon 
and  hydrogen.     These  have  a  stronger  affinity  or  attraction 
for  oxygen,  one  of  the  elements  of  the  air,  than  they  have 
tor  the  fluid  of  the  blood  in  which  they  move. 

290.  Carbon  is  one  of  the  most  important  elements  of  the 
animal  body.     It  enters  into  and  forms  a  part  of  all   flesh, 
and  of    all  vegetable  matter.     The  brain,  the  muscle,  the 


RESPIRATION.  133 

fat,  and  the  bile,  the  solid  fibre  of  the  wood,  the  pulp  of 
the  cherry,  and  the  flour  of  the  grains,  are  all  composed,  in 
a  great  proportion,  of  this  substance.  Hydrogen,  also,  is 
a  very  essential  element  in  the  composition'  of  flesh.  Com- 
bined with  oxygen,  it  forms  water ;  and  in  this  state  it  is 
found  in  the  fluids,  and  in  the  more  solid  textures  of  the  ani- 
mal body.  But  it  is  also  found,  in  different  combinations, 
with  carbon,  oxygen,  and  nitrogen,  in  the  various  kinds  of 
flesh. 

291.  It  will  now  be  necessary  to  examine  the  composition 
of  the  air.     This  is  apparently  a  simple  element ;  nothing 
seems  purer  or  less  compounded  than  air,  as  we  breathe  it. 
But  chemical  analysis  shows  it  to  be  composed  of  two  ele- 
ments, —  oxygen  and  nitrogen,  —  in  about  the  proportions  of 
twenty-one  parts  of  oxygen  to  seventy-nine  parts  of  nitrogen. 
Beside  these,  there  are  generally  some  other  gases,  —  a  little 
carbonic  acid  gas,  and  a  little  vapor,  —  amounting  to  one  or 
two  per  cent.,  in  the  atmospheric  air. 

292.  Oxygen  is  one  of  the  most  prevalent  substances  in 
nature.     It  enters  into  the  composition  of  all   animal  and 
vegetable  matter,  and  is  the  perpetually  necessary  element 
of  life,  in  all  its  forms,  and  in  all  its  stages.     It  is  the  essen- 
tial ingredient  of  most  acids.     With  sulphur  it  forms  sulphu- 
ric acid ;  with  nitrogen,  in  large  proportion,  it  forms  nitric 
acid,  or  aqua  fortis  ;  and,  in  smaller  proportion,  atmospheric 
air;  with  hydrogen,  it  forms  water;    and  with  carbon,  car- 
bonic   acid.     In   air  it   is   a  gas ;  in  water  it  is   a  liquid. 
When  separated  and  alone  it  is  a  gas ;  in  the  rust  of  iron  it 
is  solid. 

293.  Nitrogen  forms  about  four  fifths  of  the  volume  of  the 
air  we  breathe.     It  is  a  little  lighter  than  air,  and,  of  course, 
lighter  than  oxygen.     It  unites  with  oxygen  in  several  propor- 
tions, forming  very  different  substances,  according  to  the  pro- 
portions of  their  mixture.     Nothing  is  more  mild  and  bland 
than  air,  and  few  things  are  more  caustic  and  harsh  than 
aqua    fortis,  which  is  a  combination  of  the  same  elements. 

294     Although   nitrogen    and   oxygen  are  apparently  so 
12 


134  PHYSIOLOGY    AND    HEALTH. 

closely  united,  yet  the  oxygen  has  a  stronger  affinity  for  car- 
bon and  hydrogen  than  for  nitrogen ;  and  whenever,  under 
appropriate  circumstances,  the  carbon  or  hydrogen  is  pre- 
sented to  the  air,  the  oxygen  leaves  the  nitrogen  and  unites 
with  the  carbon,  and  forms  carbonic  acid,  or  with  the  hydro- 
gen, and  forms  water.  In  other  words,  the  air  is  decom- 
posed, its  simple  elements  are  separated  from  each  other,  and 
a  new  compound  is  formed  by  the  union  of  carbon  and 
oxygen,  or  by  the  union  of  hydrogen  and  oxygen. 

295.  Carbonic  acid  is  a  composition  of  oxygen  and  car- 
bon.    This  is  a  gas  heavier  than  air,  and  lighter  than  water. 
If  it  be  in  a  vessel  with  water,  it  rises  to  the  top ;  and  if  in 
a  vessel  with  air,  it  sinks  to  the  bottom.     It  is  so  much  heavier 
than  air  that  it  can  be  poured  from  one  tumbler  to  another, 
like  water.     It  is  found  in  some  caves,  and  at  the  bottom  of 
some  wells.     It  is  the  fixed  air  which  is  the  product  of  fer- 
menting bread,  beer,  wine,  and  cider,  and  fills  the  bubbles 
that  rise  to  the  top  of  these  liquids  at  the  time  of  their  fer- 
mentation.    When  the  beer  is  drawn  out  from  the  vats,  in 
the  great  breweries,  this  gas  often  falls  to  the  bottom,  and 
partially  fills  these  reservoirs.     It  is  also  the  product  of  com- 
bustion of  charcoal ;   and  often,  where  this  fuel  is  burning 
without  any  outlet  near  the  floor  for  this  gas  to  run  off,  or  a 
chimney  of  sufficient  draft  to  carry  it  upward,  it  partially  or 
entirely  fills  the  room.     Wherever  this  gas  is,  there  can  be 
no  pure  air,  for  this  is  excluded  by  it  as  certainly  as  it  would 
be  by  water ;  and  it  is  as  unsafe  for  a  man  to  enter  a  cavern, 
well,  vat,  or  a  room  containing  it,  and  carry  his  head  below  the 
surface  of  this  gas,  as  it  would  be  if  these  contained  water. 

296.  When  the  chest  expands,  the  air  rushes  in  and  fills 
all    the    air-tubes    and   the    air-cells  throughout   the    lungs. 
There  it  comes   almost  in  contact  with  the  venous  blood, 
which  is  distributed  in  the  numberless   little   vessels,   and 
separated  from  the  air-cells  only  by  a  thin  film  of  memlrane, 
through  which  the  gases  can  pass.     There  an  interchange 
takes  place  between  the  fluid  and  the  gas.     The  blood  ab- 
sorbs from  the  air  some  of  its  oxygen,  and  the  air  takes  from 


KESPIRATIOX.  135 

the  blocd  some  of  its  carbonic  acid  and  its  water.  By  this 
change  the  blood  is  relieved  of  its  exhausted  and  dead  parti- 
cles, and  receives  new  and  life-giving  particles  in  their  stead. 
The  color  is  changed  from  a  dark  purple  to  a  bright  scarlet. 
After  this,  the  blood  is  ready  again  for  the  sustenance  of  life, 
and  is  sent  back,  through  the  pulmonary  veins,  to  the  left 
side  of  the  heart,  to  be  sent  again,  through  the  arteries,  to 
the  whole  of  the  body,  carrying  nutriment  to  support  it,  and 
oxygen  to  combine  with  its  dead  carbon. 

297.  Carbon  and  hydrogen  compose  the  principal  portion 
of  the  wasted  and  exhausted  particles  of  the  living  body,  and 
these  are  thrown  into  the  veins.  There  they  meet  with  the 
oxygen  that  has  been  absorbed  from  the  atmosphere  in  the 
lungs,  and  carried  in  the  blood,  through  the  arteries,  to  the 
capillaries  and  the  minute  veins.  There  these,  the  hydrogen 
and  the  carbonic  particles,  and  the  oxygen,  meeting  together, 
unite  and  form  carbonic  acid  gas  and  water.  These  new 
compounds  are  then  sent,  with  the  venous  blood,  through 
the  veins,  to  the  heart,  and  thence  to  the  lungs. 


CHAPTER  V. 

Venous  or  purple  Blood  changed  to  arterial  or  scarlet  Blood.  — 
Color  of  venous  Blood  seen  in  Veins  of  Hand,  and  of  arterial 
Blood  in  flushed  Cheek.  —  Oxygen  consumed  in  Respiration.  — 
Carbonic  Acid  given  out.  —  Water  given  out  through  Lungs.— 
Other  Matters.  —  Foul  Odors  in  Breath.  —  Offensive  Breath. 

298.  THE  blood  enters  the  lungs  a  compound  of  three 
kinds  of  matter  —  the  old  blood,  which  had  not  been  used  for 
the  purpose  of  nutrition,  the  old  wasted  particles,  which 
are  now  seeking  an  outlet,  and  the  new  chyle  from  the 
digestive  organs.  (§  264,  p.  120.)  All  this  heterogeneous 
mass  is  unfit  for  the  nutrition  of  the  animal  body.  Its  color 
is  purple.  In  this  compound  no  free  oxygen  is  present,  but 
carbonic  acid  and  water  are  abundant.  When  the  blood 


136  PHYSIOLOGY    AND    HEALTH. 

returns  back  to  the  heart  from  the  lungs,  it  is  one  homoge- 
neous compound ;  it  has  lost  its  carbonic  acid  and  water,  and 
received  a  supply  of  oxygen,  which  now  pervades  the  fluid. 

299.  The  difference  of  the  color  of  the  blood  is  seen  in 
the  veins  of  the  hand  and  arm,  which^appear  to  be   blue, 
while  the  flushed  cheek  is  of  scarlet  red,  from  the  presence 
of  the  blood  in  the  arteries  of  the  skin.     When  a  person  is 
bled  from  the  arm,  the  vein  is  opened ;  the  blood  that  flows 
is  venous,  and  of  course  purple.     The  inexperienced  mistake 
this  natural  color  for  the  effect  of  disease,  and  often  remark, 
"  that  the  blood  is  very  black ;  the  patient  needed  bleeding 
to  be  relieved  of  such  dark  impurities." 

300.  This  change  of  the  blood  is  effected  in  the  lungs , 
of  course,  there  must  be  a  corresponding  change  in  the  air. 
The  oxygen  which  the  blood  receives  is  the  oxygen  of  the 
air ;  and  the  carbonic  acid  and  water  which  are  thrown  off 
from  the  blood  are  mingled  with  the  air.     The  air  is  therefore 
changed  by  this  process,  and  to  this  extent.     During  a  state 
of  repose,  the  air  at  each  respiration  has  a  little  more  than 
four  per  cent,  of  its  volume  of  carbonic  acid  gas  added  to 
it,  and  the  oxygen  is  diminished  in  proportion  necessary 
to  form  this  acid.     If  the  same    air  be  respired   over  and 
over   several   times,  all  the  oxygen   is   consumed,   and  the 
air  becomes  loaded  with  carbonic  acid  gas. 

301.  Sir  Humphry  Davy  enclosed   one  hundred  and  sixty 
cubic  inches  of  air  in  an  oiled  silk   bag,  and  breathed   this 
for  the  space  of  one  minute.     In  this  time,  he  made  nineteen 
respirations.     On    examination   of  the    air,    he   found   that 
nearly  one  half  '(if  if )  of  the  oxygen  was  consumed,  and  its 
place  supplied  by  15.2  inches  of  carbonic  acid,  which  had 
been  generated  in  the  blood-vessels,  and  given  out  from  the 
lungs  in  one  minute.f 

302.  The  quantity  of  carbonic  acid  gas  which  is  found 
in  the  air  that  has  been  breathed,  varies  in  different  circum- 
stances,   and    in    different    conditions   of  the  human    body. 

*  Lehmann's  Physiological  Chemistry,  Vol.  II.  436. 
f  Mullcr's  Physiology,  p.  295. 


KESPIRATION.  137 

It  is  greater  in  the  waking  than  in  the  sleeping  hours.  It 
is  more  when  the  body  is  in  action  than  when  at  rest ;  in 
winter  than  in  summer.  It  is  greater  when  the  body  is  well 
nourished  than  when  fasting.  Vlerordt  found  that  the 
quantity  discharged  was  fourteen  per  cent,  greater  two 
hours  after  he  had  dined  than  it  was  on  other  days  at  the 
same  hour,  when  the  dinner  had  been  omitted.* 

303  Besides  the  carbon  of  the  blood,  which  is  to  be  car- 
ried away  through  the  lungs,  there  is  water  which  is  not 
needed  in  the  body,  and  which  finds  its  passage  through  the 
same  outlet.  This  water  goes  out  in  the  form  of  vapor,  and 
ordinarily  is  not  perceptible.  But  every  one  is  familiar  with 
the  visible  cloud  of  vapor  that  accompanies  his  breath  in  a 
cold  winter's  morning.  This  is  but  the  condensation  of  the 
vapor  that  is  invisible  in  a  warm  day.  The  same  may  be 
ascertained  at  any  time  by  breathing  on  a  looking-glass, 
when  the  vapor  is  condensed,  and  becomes  visible  in  the  form 
of  water. 

304.  There  are  other  matters  carried  off  from  the  body 
through  the  lungs  by  the  air.  Their  perceptible  qualities 
differ  in  various  men.  The  breath  from  one  is  sweet,  from 
another  sour,  from  a  third  foul  and  offensive,  and  from  a 
fourth,  it  is  without  perceptible  odor.  These  disagreeable 
odors  may,  in  some  cases,  proceed  from  decayed  teeth,  or 
from  disease  in  the  mouth,  the  air  passages,  or  the  lungs ; 
but  more  commonly  they  come  from  direct  secretions  in  the 
lungs  of  certain  matters,  which  existed  previously  in  the  ani- 
mal body ;  as,  when  one  has  eaten  onions,  his  breath  smells 
of  garlic.  The  odor  of  wine  or  spirits  which  have  been 
taken  into  the  stomach,  is  perceptible  in  the  breath,  long 
after  the  mouth  has  been  thoroughly  cleansed  of  these  mat- 
ters. In  other  cases,  these  unpleasant  odors  proceed  directly 
from  some  foul  secretion  in  the  lungs.  The  habit  of  chew- 
ing or  smoking  tobacco  gives  to  one's  breath  an  odor  pe- 
culiarly offensive  to  others  who  may  inhale  the  same  air. 
In  some  persons,  this  odor  is  so  powerful  as  to  taint  the  air 
of  a  whole  room  as  soon  as  they  enter  it. 

*  Lchmanu's  Physiological  Chemistry,  Vol.  II. 


138  PHYSIOLOGY    AND    HEALTH. 


CHAPTER    VL 

Air  changed  by  Respiration  unfit  to  be  breathed  again.  — Dyer  col- 
ors  with  Dye  of  full  Strength.  —  Air  should  have  full  Proportion  of 
Oxygen.  —  Respired  Air,  loaded  with  Carbonic  Acid  Gas,  can  take 
away  no  more.  —  Air  saturated  with  Water  can  take  no  more 
from  Lungs.  —  Air  spoiled  for  Respiration  in  three  Ways. 

305.  AN  examination  of  the  air,  after  it  has  passed  out  of 
the  lungs,  shows  that   it  is  very  different  from  the  same  air 
before  it  went  in.     At  first,  it  had  about  twenty-one  per  cent. 
of  oxygen,  seventy-eight  per  cent,  of  nitrogen,  and  one  per 
cent,  of  carbonic  acid ;   but,  when  it  has  been  respired,  it  has 
lost  about  one  fourth  of  its  oxygen,  and  has  gained  carbonic 
acid  and  vapor,  in    proportions  varying  with  many  circum- 
stances connected  with  the  state  and  health  of  the  animal 
system.     If,  then,  it  is  necessary  for  the  blood  to  consume  at 
each  respiration  one  fourth  of   the  oxygen  of  the  air  which 
is  inhaled,  it  would  follow  that,  if  the  same  air  be  breathed 
twice,  one  half  of  the  ox'ygen  would  be   consumed ;  and  if 
breathed  three  times,  three  quarters;  and  if  breathed  four 
times,  all  would  be  consumed.     If  so  much  oxygen  is   not 
consumed,  there  must  be  so  much  less  of  the  carbon   and 
the  waste  of  the  blood  carried  away. 

306.  But,  if  the  Jungs  consume  only  one  fourth  of  its  oxy- 
gen at  each  respiration,  it  by  no  means  follows  that  the  air 
can  b£  breathed  four  times  over,  and  at  each  time  have  the 
same  effect  in  purifying  the  blood.     In  respect  to  relieving 
the  blood  of  the  carbon,  the  oxygen  may  be  considered  as 
the  strength  of  the  air.     When  this  constitutes  twenty-one 
per  cent.,  it  is  of  full  strength;  when  it  is  only  fifteen  per 
cent.,  it  is  only  three  quarters  of  full  strength ;   and,  at  most, 
it  can  have  only  three  quarters  of  the  due  power.     So,  when, 
after    being  once   respired,    it    is    reduced   by   another  and 
another  respiration    to   one    half    and    one   quarter  its    full 
strength,  it,  of  course,  has  so  much  less  power  of  performing 
that  which  is  required  of  it. 


RESPIRATION.  139 

307.  When  the  dyer  has  determined  what  strength  of  dye 
will  give  the  due  color  to  his  cloths,  he  adds  fresh  coloring 
matter  as  often  as  one  piece  has  weakened  it,  in  order  to 
keep  up  the  dye  to  its  full  strength,  and  to  give  to  each  suc- 
cessive piece  of  cloth   the   same  hue ;    for,   if  the  dye  be 
weakened,  it  will  give  a  weaker  color.     He  would  not,  there- 
fore, continue  to  dip  his  cloths  in  it,  after  it  is  reduced,  be« 
cause  there  was  some  coloring  matter  left;    nor   would   he 
think  of  exhausting  all  the  power  of  the  dye,  unless  he  was 
satisfied  to  produce  a  duller  shade. 

308.  Precisely   analogous  to  this  is  the  effect  of  the  air 
in  purifying  the  blood  of  its  corrupting  carbon.     The  stronger 
the  air,  —  that  is,  the  greater  the  proportion  of  its  oxygen, — 
the  more  effectually  will  this  carbon  be  carried  away ;  the 
weakened  air  must  produce  a  weak  effect,  artd  take  away  less 
of  the  impurities.     Air,  therefore,  which  has  been  breathed 
once  or  more,  having  lost  a  certain  part  of  its  oxygen,  must 
be,  in  that  proportion,  unfit  to  do  the  work  of  respiration. 
If  we  breathe  pure  oxygen,  or  air  too  strongly  oxygenated, — 
that  is,  air  containing  more  than  twenty-two  per  cent,  of  this 
gas,  —  the  carbon  would  be  taken  from  the  blood  faster  than 
it  could   be  spared,  and  the  body  would  be  wasted.     If  we 
breathe  air  containing  less  than  twenty-one  or  twenty-two  per 
cent,  of  oxygen,  it  will  not  carry  the  carbon  off  so  fast  as  is 
required.     It  is  only  by  breathing  air  of  the  natural  strength 
that  this  work  is  best  performed,   and   the   carbon    carried 
away   neither  too    rapidly  nor   too  slowly.     Air,   therefore, 
should  be  breathed  once,  and  once  only.     We  need  a  fresh 
draft  of  air  at  every  inspiration,  as  much  as  the  dyer  needs  a 
fresh  dye  at  every  coloring. 

309.  Air,  when  it  has  been  breathed,  not  only  loses  its 
oxygen,  which  is  its  active  principle,  but  it  is  loaded  more 
or  less  with  carbonic  acid  gas,  which  is  increased  by  every 
respiration.     Therefore,  when  we  breathe  air  over  and  over, 
we  not   only   breathe  a  weaker  gas,  but  a  fouler  one;  we 
receive  back  into  the  lungs,  and  into  the  vital  system,  that 


140  PHYSIOLOGY    AND    HEALTH. 

dead  and  corrupting  matter  which  nature  had  so  carefully 
removed. 

310.  There  is  another  consideration  in  this  matter.     Sup- 
posing the  air  were  merely  a  passive  vehicle  to  carry  off  the 
carbonic  acid  gas,  and  had  no  active  duty  in  the  work,  it 
would  be  a  natural  question  to  ask,  How  much  of  this  gas 
can  it  bear   away?     Is  there    any  limit  to  its  capacity  of 
taking  up  and  bearing  off  this  offending  matter  ?     Now,  it  is 
well  established  that  the  air  will  not  receive  and  hold  an  in- 
definite quantity ;  but,  after  having  received  a  certain  propor- 
tion, it  will  receive  no  more.     When  it  has  arrived   at  this 
point  of  saturation,  —  that  is,  when  it  is  so  full  that  it  can 
receive  no  more,  —  it  then  is  useless  as  a  vehicle  to  carry  off 
any  more   from  the  lungs.     Bernan  says  *  that,  when  the  air 
holds  in  solution  only  about  three  and  a  half  per  cent,  of  its 
bulk  of  carbonic  acid  gas,  it  is  unfit  for  respiration. 

311.  The  air,  for  this  purpose,  may  be  considered  as  the 
water  which  the  dyer  would  use  to  wash  his  colored  cloths. 
It  is  plain  that,  when  the  water  is  once  befouled  or  saturated 
with  the  loose  coloring  matter,  it  would  take  no  more  from 
the  cloths ;  and  therefore  the  judicious  cleanser  changes  his 
waters  as  often  as  they  become  foul ;  and,  whenever  he  can, 
he  selects  a  running  stream,  so  that  the  water   is  carried 
away  as  fast  as  it  is  befouled,  and  its  place  is  supplied  with 
fresh  and  clean. 

312.  Upon  the  same  principle,  the  lungs  cannot  be  thor- 
oughly   cleansed    of    the   impurities   which    come    to   them 
through  the  blood,  unless  the  air  is  supplied  to  them  fresh 
and  untainted  at  every  respiration.     For  foul  air,  loaded  with 
carbonic  acid  gas,  can  no  more  cleanse  the  lungs,  than  foul 
water  can  cleanse  the  colored  cloths. 

313.  The   blood  is  relieved  of  its  superabundant   water 
through  the  lungs.     Tf  this  does  not  find  an  outlet  here,  and 
if  it  is  not  carried  off  by  the  air,  it  must  be  carried  back  in 
the  blood  to  the  heart  and  the  arteries,  to  overload  the  sys- 

*  Art  of  Warming  and  Ventilation. 


RESPIRATION.  141 

tern  and  impede  its  operations.  There  is  a  definite  quantity 
which  must  be  carried  out,  and  the  air  has  a  limited  capacity 
for  holding  water,  and  of  taking  it  away.  When  this  limit  is 
reached,  and  the  air  is  saturated  with  water,  it  can  take  up 
no  more.  The  air  would  be  saturated  with  moisture  from 
the  lungs  in  about  the  same  number  of  respirations  that 
would  consume  its  oxygen ;  after  this,  it  would  be  useless  for 
the  removal  of  either  carbon  or  water. 

314.  Thus  we  see  that,  in  three  ways,  the  air  becomes 
vitiated,  and  unfit  for  continued  respiration  :  1st,  by  the  con- 
sumption of  its  oxygen,  so  that  it  is  unable  to  remove  the 
carbon  from  the  blood ;  2d,  by  being  loaded  with  carbonic 
acid  gas,  so  that  it  cannot  take  it  up  any  longer  from  the 
lungs :  3d,  by  being  saturated  with  moisture,  so  that  it  can- 
not aid  in  relieving  the  system  of  its  superabundance  of 
water. 


CHAPTER   VII. 

More  Oxygen  consumed,  and  Carbonic  Acid  given  out,  in  cold  and 
dense  Air,  and  less  in  warm.  —  Air  on  Mountains  does  not  sup- 
port Life  as  in  Valleys.  —  Impurities  in  Air  diminish  Oxygen. — 
Feeble,  consumptive,  and  melancholy  Persons  give  out  less 
Carbon  and  Hydrogen. 

315.  THE  amount  of  oxygen  received,  and  the  quantity 
of  carbonic  acid  gas  and  watery  vapor  carried  off,  differ  at 
different  times,  and  vary  with  varying  circumstances.  A 
dense  atmosphere  is  more  concentrated,  and,  consequently, 
contains  more  oxygen  in  a  given  space,  than  a  rare  one.  The 
air  is  more  expanded  in  a  warm  than  in  a  cool  climate,  and 
in  hot  than  in  cold  weather.  We  therefore  do  not  inhale  so 
great  a  weight  of  air,  and,  consequently,  so  great  an  amount 
of  oxygen,  in  summer  as  in  winter.  The  oxygen  received 
being  less,  the  carbonic  acid  given  out  is  diminished  in  the 
same  proportion. 


142  PHYSIOLOGY    AND    HEALTH. 

316.  We  experience  faintness  and  languor  in  the  warm 
season,  because  the  air  does  not  purify  a  sufficiency  of  blood 
for    the   vigorous   sustenance   of  the  system.     Then  people 
complain  that  "  the  air  is  heavy,"  which  is  directly  opposite 
to  the  truth,  for  the  air  is  really  light,  and  it  does  not  contain 
sufficient   oxygen    to   invigorate   them,    and    give   sufficient 
strength  and  elasticity  to  bear  the  burdens  and  operations  of 
life  easily,  and  hence  all   these  are  heavy  to  them.     We  ob- 
serve animals  puff  and  breathe  rapidly  after  running  in  sum- 
mer, and  we  do  the  same  on  any  active  exertion,  more  in 
warm  than  in   cold  weather.     We  do  this  to  bring  a  more 
frequent  supply  of  air  to  the  blood,  and  thus  to  compensate 
for  the  lightness  of  the  air,  and  deficiency  of  oxygen,  by  the 
rapid  renewal  of  both. 

317.  The  air  is  more  dense  in  the  lower  regions  of  the 
earth,  and  on  the  level   of  the  sea,  than  on  the  heights  of 
mountains.     As  we  ascend  from  below  to  the  higher  eleva- 
tions, we  find  the  air  lighter  and  more  expanded,  and  we  are 
compelled  to  breathe  more  rapidly.     Travellers  all  complain 
of  the  increasing  languor  and  faintness  as  they  ascend,  and 
enjoy  the  bracing  and  invigorating  effect  of  the  air  as  they 
come  down  the  mountains. 

318.  All  kinds  of  impurities  in  the  air,  and  every  thing 
that   diminishes  the   proportion  of  oxygen,   have  the   same 
effect  of  weakening  or  diminishing  the  vital  properties  of  the 
air.     In  some  mines,  a  gas  is  given  out,  called  ihejire  damp, 
which  is  carburetted  hydrogen.     Whenever  this  is  present, 
it  lessens  the  vivifying  power  of  the  air,  by  excluding  its  oxy- 
gen.    If  it  is  breathed  in  small  quantities,  it  occasions  gid- 
diness, sickness,  and  diminished  nervous  power ;  and,  when 
it  is  in  great  proportion,  the  miners  are  unable  to  breathe, 
and  often  fall  a  sacrifice  to  it. 

319.  The  general  state  of  the  system  affects  the  quantity 
of  matter  which  is  carried  out  through  the  lungs.     When 
the  whole  frame  is  well,  and  all  the  functions  are  carried  on 
vigorously,  —  when  the  circulation  of  the  blood  is  easy  and 
the  respiration  well  sustained,  —  then  the  old  particles  of  the 


RESPIRATION.  143 

body  are  freely  separated,  and  the  new  and  vitalized  ones 
take  their  places,  and  the  former  are  carried  rapidly  away, 
and  life  is  frequently  renewed,  and  vigorously  sustained. 
But  when  the  system  is  feeble  and  languid,  —  when  it  is  fever- 
ish and  generally  disturbed,  —  when  it  is  exhausted  by  fa- 
tigue or  want  of  sleep,  —  the  reverse  happens  ;  the  circulation 
is  languid,  the  nutrition  feeble,  absorption  slow,  and  a  smaller 
proportion  of  carbon  and  hydrogen  is  carried  off. 

320.  The  system  is  relieved  of  these  dead  matters,  more  or 
less,  according  to  the  condition  of  the   lungs,  in  proportion 
as  they  are  healthy  or  unhealthy.     In  some  diseases,  their 
texture  is  changed  from  an  exceedingly  porous  and  spongy 
body,  to  one   partially  or  entirely    solid.      In  consumption, 
a  part  of  these  organs  is  filled  with  tubercles,  or  abscesses. 
Sometimes  these  occupy  almost  the  whole  substance  of  the 
lungs,  and  leave  so  little  room  for  air  that  respiration  can- 
not be  carried  on.     Then  the  sufferer  literally  dies  for  want 
of  breath,  because  the  lungs  cannot  receive  sufficient  air  to 
purify  as  much  blood  as  is  necessary  to  sustain  life.     The 
impure  blood  which  cornes  to  the  lungs,  to  exchange  its  car- 
bon for  oxygen,  does  not  find  air  to  give  it  relief,  and  goes 
back  to  the  heart  nearly  as  corrupt  as  when  it  came  out. 

321.  In  lung  fever,  and  some  other  diseases,  a  portion  of 
the   lungs  becomes  solid,   like  liver,   and  the   air-cells   are 
closed.     If  the  whole   of  the   lungs  becomes  consolidated, 
death  must  follow ;  but  this  state  more  frequently  prevails  in 
a  part  only  of  these  organs  ;  then  the  blood  is  sent  back  in  an 
imperfect  condition,  and  the  frame  is  then  only  partially  nour- 
ished.    Some  have  sustained  life  for  a  considerable  period 
with  only  one  sound  lung ;  but  theirs  was  a  feeble  and  lower 
life,  and  they  could  not  perform  all  the  work,  nor  enjoy  all 
the  comforts,  of  ordinary  well-sustained  existence. 

322.  The  states  of  the  mind  and  feeling,  as  well  as  those 
of  the  body,  affect  the  discharge  of  waste  matters  through 
the  lungs.     Cheerfulness  and  exhilaration,  and  the  exciting 
passions,  increase  the  separation  of  carbon  ;    while  the  de- 
pressing emotions  —  fear,  grief,  and  anxiety  —  diminish  it. 


144  PHYSIOLOGY   AND    HEALTH. 


CHAPTER   VIII. 

Lungs  must  have  Capacity  to  receive  sufficient  Air.  —  Action  of 
Respiration  performed  by  the  Muscles  of  Chest  and  Diaphragm.— 
Ribs  spread  outward  in  Inspiration.  —  Action  of  Diaphragm 
presses  the  Abdomen  downward  and  outward. 

323.  IT  is  not  only  necessary  that  the  lungs  should  be  in 
good  health,  and  be  supplied  with  pure  air,  but  they  should 
be  able  to  receive  it  in  sufficient  quantity.     This  implies  that 
the  chest  should  be  of  the  natural  size,  and  that  it  should 
have  the  due  power  and  opportunity  of  expansion  and  con- 
traction. 

324.  Although   it    is    absolutely  necessary  that   the   air 
reach  the  blood  in  the  lungs,  yet  it  has  no  active  power  to 
get  there.     It  is  merely  passive.     It  does  not  enter  of  its  own 
accord,  but  it  is  pressed  into  these  organs,  when,  by  the  en- 
largement of  the  cavity,  a  vacuum,  or  rather,  more  room,  is 
made  for  it.     Nor  have  the  lungs  any  active  power  of  expan- 
sion.    They,  too,  are  merely  passive.     Their  air-cells  do  not 
extend   themselves,    and   thus   press  the  walls  of  the  chest 
outward.     But,  when  these  walls  are  extended,  the  air  rushes, 
or  rather  it  is  pressed,  into  these  air  tubes  and  cells,  and  com- 
pels the  lungs,  thus  filled  with  air,  to  swell  and  completely  fill 
the  cavity  of  the  chest. 

325.  The  structure  of  the  chest  is  arranged  like  the  com- 
mon bellows  for  expansion  and  contraction.  (§§  270 — 277,  pp. 
122,  125.)     The  bony  framework  is  furnished  with  joints,  on 
which  the  ribs  move.     The  muscular  covering  contracts  and 
sets  this  framework  in  motion,  while  the  diaphragm  draws 
down,  and  both  cooperate  to  enlarge  the  internal   capacity 
of  the  pulmonary  cavity;  then  the  ribs  fall,  and  the  abdom- 
inal muscles  press  the  diaphragm  up,  and  both  combine  to 
diminish  this  cavity. 

326.  In  Fig.  XXL,  the  full  black  lines  represent  the  out- 
line  of  the  chest  and  the  abdomen  when  the  lungs  are  empty, 
and  the  dotted  lines  represent  the  same  when  the  lungs  are 


RESPIRA 


145 


filled  with  air.  When  the  air  is  inhaled,  the  walls  of  the 
chest  are  expanded  from  a,  e,  to  «,  6,  and  the  diaphragm 
drawn  down  from  e,  c?,  to  6,  of,  and  consequently  the  walls  of 
the  abdomen  are  carried  from  e,  e,  to  6,  c,  and  the  diameters 
of  both  are  increased. 

FIG.  XXI.    Side  Flew  of  expanded  and  contracted  Chest. 


e,  d,  Diaphragm  drawn  up. 
6,  d,  Diaphragm  drawn  down. 

a,  e,  c,  Front  wall  of  contracted  chest  and 
abdomen. 

a,  b,  c,  Front  wall  of  expanded  chest  and  ab- 
domen. 


327.  This  expansion  of  the  chest  and  abdomen  cannot 
take  place  unless  there  is  room  outwardly.     If  the  body  is 
enclosed  in  any  inelastic  girdle  or  dress  which  fits  it  closely 
when  the  chest  is  empty,  it  must  be  confined  within  that 
limit,  and  its  expansion  prevented. 

328.  Some  of  the  fashions  of  the  dress   of  females   of 
modern  times,  and  in  civilized  nations,  have  precisely  the 
effect  of  bandages  to  confine  the  ribs,  and  limit  the  expansion 
of  the  chest,  and  prevent  the  inhaling  of  the  due  quantity  of 
air.     The  corsets  are  made  of  inelastic  materials,  and  usu- 
ally so  constructed  and  laced  as  to  exactly  fit  the  shape  of 
the  bust,  and  lie  as  closely  to  the  surface  as  possible.     When 
these  are  worn,  and  the  other  garments  are  arranged  upon 


140  PHYSIOLOGY   AND    HEALTH. 

the  same  principle,  and  with  their  fastenings  bound  closely 
to  the  body,  so  as  to  mould  the  form,  they  confine  the  ribs, 
and  prevent  their  movements  upward  and  outward. 

329.  In  this  confinement  of  garments,  whenever  the  mus- 
cles attempt  to  raise  the  ribs  and  extend  them  outward,  they 
meet  with  resistance.     These  muscles  are  not  very  strong ; 
they  are  made  for  a  definite  purpose  —  merely  to  raise  the  free 
ribs,  and  to  expand  the  unobstructed  chest,  but  not  to  break 
bands,   force   lacings,   or  stretch   layers   of  compact    cloth. 
Hence,  finding  all  labor  ineffectual,  they  after  a  while  cease 
their  attempts  to  move  the  ribs,  or  at  least  diminish   their 
exertions  very  materially,  and  leave  the  main  business  of 
respiration  to  be  done  by  the  diaphragm. 

330.  When  the  diaphragm   descends  out  of  the  cheit,  it 
must  press  the  digestive  organs  downward  before   it.     But 
these  organs  cannot  be  compressed ;  they  are  not  made  to 
occupy  less  room  than  before ;  they  are  merely  removed  from 
their  upper  position  to  a  lower  and  a  broader  one.     There- 
fore they  must  find  room  for  extension  below  and  outward. 
And  if  this  is  prevented,  —  if  the  abdomen  is  so  bound  or 
compressed  that  it  cannot  expand,  —  the  stomach  and  liver 
cannot  give  way  before  the  diaphragm,  and  then  this  muscle 
cannot   descend   to  make   room  for  the  lungs,  nor  can  we 
breathe  by  this  part  of  the  respiratory  apparatus. 

231.  The  consequence  is,  whenever  the  fashion  of  the 
female  dress  extends  the  pressure  of  the  waist  beyond  the 
ribs,  and  encloses  a  good  portion  of  the  abdomen,  unless  quite 
loose,  or  whenever  the  costume  of  the  male  presses  upon 
this  part  of  the  body,  it  must  interfere  with  the  freedom  of 
motion  of  that  part  of  the  system,  and  so  far  prevent  or 
restrict  respiration  by  the  diaphragm. 


RESPIRATION.  147 


CHAPTER   IX. 

Common  Notion  of  Beauty  of  Chest  unnatural.  —  Chest  Seat  of  most 
important  Organs.  —  Size  of  Chest  corresponds  to  Size  of  Body.  — 
Natural  Chest  not  conical.  —  Shape  of  Bones  changed  by  Pres- 
sure.—  Comparative  Form  of  Chests. 

332.  THERE  is  a  common  and  mistaken  notion  of  beauty 
of  the  female  chest.     The  beau  ideal  of  many  requires  that 
it  should  be  of  a  small  and  taper  form,  diminishing   from 
the    shoulders    downwards    to   the   waist.     This    opinion   is 
encouraged    and  strengthened  by  the  fashion  of  female  gar- 
ments.    But  however  general  this  form  may  be,  and  however 
Jong  established  in  the  world,  it  is  artificial, ^and  not  natural. 
It  is  opposed  to  that  principle  of  beauty  which  nature  has 
clearly  and  every  where  established  —  that  grace  is  secondary, 
and  not  primary ;  that  it  is  the  proper  and  becoming  arrange- 
ment of  those  parts  that  are  necessary  and  useful. 

333.  The  chest  is  not  a  mere  connecting  link  between 
the  upper  and  lower  portions  of  the  animal  frame ;  but  it  is  the 
depository  and  the  workshop  of  some  of  the  most  important 
of  the  vital  organs,  without  the  action  of  which  life  cannot 
be  for  a  moment   sustained,  and    without  whose  free   and 
perfect  operation  life  must  be  impaired  and  enfeebled. 

334.  As  the  chest  is  made  for  the  use  of  the  body,  and 
not  for  ornament,  —  as  it  was  created  to  contain  the  heart, 
and  to  give  room  and  motion  to  the  lungs,  so  that  respiration 
could  be  carried  on  in  the  best  manner,  —  it  would  follow  that 
that  form  and  size  of  this  part  of  the  animal  frame  is  the 
most  beautiful,  which  would  best  answer  these  purposes,  and 
allow  the  lungs  to  perform  their  functions  most  effectually. 

335.  The  size  of  the  chest  should  bear  a  proportion  to 
the  size  of  the  body,  so  that  it  may  receive  a  quantity  of  air 
proportioned  to  the  quantity  of  blood  that  must  be  purified 
in  the  system.     Therefore,  a  small  waist  becomes  only  a  small 
person,  and  a  large  waist  is  necessary  to  the  grace  of  a  large 


148 


PHYSIOLOGY   AND   HEALTH. 


person,  precisely  as  a  large  or  small  head  is  becoming  to  a 
frame  proportionally  large  or  small. 

336,  This  is  the  plainly  established  principle  of  Nature. 
We  see  it  in  all  her  works.  If  we  examine  the  little  child, 
who  has  never  worn  any  close  dress,  we  find  the  circumfer- 
ence of  its  chest  about  as  great  as  that  of  the  body  at  the 
hips,  and  a  line  from  the  arm-pit  to  the  hip  would  be  nearly 
straight.  If  the  waist  is  never  subjected  to  the  pressure  of 
clothing,  which  would  interfere  with  the  motions  of  the  ribs, 
the  chest  will  be  continued  through  life  in  nearly  the  same 
shape  as  that  of  the  child,  (Fig.  XXIII.,)  or  of  the  Indian 
female,  whose  garments  have  never  been  bound  about  the 
chest.  We  see  the  same  in  many  laborers,  more  especially 
those  from  the  middle  and  the  north  of  the  continent  of  Eu- 
rope. The  ancient  statues  show  the  full  chest,  the  expanded 
waist,  and  the  broad  freedom  of  the  lungs  for  motion. 


FIG.  XXII. 


FIG.  XXIII. 


337.  But  the  chests  of  many  who  are  incased  in  a  close 
costume  are  small,  and  taper  downwards  from  the  shoulder 


RESPIRATION.     ^  149 

to  the  waist,  (Fig.  XXII.)  In  some,  this  is  the  temporary 
effect  of  present  pressure ;  and  when  the  close  garments  are 
taken  off,  the  ribs  rise  to  their  natural  position,  and  the  chest 
expands  to  its  natural  size.  But  in  others,  whose  chests 
have  been  long  subjected  to  this  close  confinement,  this  dis- 
tortion of  ribs  and  contraction  of  chest  become  fixed  and 
permanent  ;  and  then  they  need  no  outward  covering  to  con- 
fine the  respiratory  organs  within  these  narrow  dimensions. 

338.  Figure  XXIII.  represents  the  chest  of  those  who  have 
always  worn  loose  dresses.  Fig.  XXII.  is  that  of  one  used 
to  tight  dresses.  The  former  receive  much  more  air  into 
their  lungs,  and  carry  off  the  impurities  of  their  blood  more 
freely,  and  hence  their  changes  of  particles  must  be  more 
rapid,  their  vigor  and  elasticity  of  body  must  be  much 
greater  than  the  others  enjoy.  •* 

FIG.  XXIV.  FIG.  XXV. 

Bones  of  a  natural  Chest.  Bones  of  a  distorted  Chest. 


339.  The  bony  frame  by  pressure  may  be  altered,  and 
made  to  assume  forms  very  different  from  that  which  nature 
intended.  In  the  process  of  nutrition,  (§§  244-247,  pp.  112, 
114,)  the  old  particles  of  the  animal  body,  in  all  its  parts, 
are  continually  going  away,  and  new  ones  are  taking  their 
places.  But  if  any  pressure  bear  upon  the  depositing  vessels 


150  PHYSIOLOGY    AND    HEALTH. 

on  one  side  and  close  them,  the  new  particles  are  not  placed 
there,  but  the  blood  is  poured  more  freely  into  the  other  side, 
and  there  the  growth  is  increased ;  and  thus  the  shape  of  the 
organ,  the  bone,  or  the  flesh,  is  changed. 

340.  This  distortion  necessarily  follows  in  the  form  and 
size  of  the  ribs,  from  the  pressure  of  corsets  or  any  tight 
clothing  upon  them.  They  gradually  yield  to  the  external 
form,  and,  bending  inward,  assume  the  shape  which  the  outer 
mould  makes  for  them ;  and  the  chest,  which  was  originally 
of  a  size  in  due  proportion  to  the  rest  of  the  body,  now  be- 
comes permanently  small,  and  the  internal  capacity  of  the 
lungs  corresponds  to  the  external  measurement.  Fig.  XXV. 


CHAPTER  X. 

Action  of  Diaphragm  is  affected  by  State  of  Stomach.  —  Frequency 
of  Respiration,  Capacity  of  Lungs,  Amount  of  Air  inhaled,  should 
correspond  with  the  Carbon  and  Water  that  are  to  be  carried  away. 
—  Quantity  of  Blood  in  the  Body.  —  Quantity  of  Blood  and  Air 
flowing  through  Lungs. 

341.  THE  free  operations  of  the  diaphragm  are  sometimes 
impeded  by  the  disorders  of  the  stomach.     In  some  forms  of 
dyspepsia,  the  sufferer  feels  as  if  the  cavity  of  the  chest  were 
already  filled,  and  that  no  more  air  could  be  inhaled.     He 
breathes  short,  and  is  often  convinced  that  there  must  be 
serious  disease  of  the  lungs.     In   some  of  these  cases,  the 
stomach  is  distended   with  gas,   and  presses   upward  upon 
the  diaphragm  so  as  to  prevent  its  motions  downward.      In 
other  cases,  the  peculiar  kind,  rather  than  the  quantity,  of 
gas  affects  this  organ  and  impairs  its  power  of  motion. 

342.  A  man  in  good  health  will  breathe  about  eigJiteen 
times  a  minute.     Some  breathe  more  rapidly  than  this  ;  oth- 
ers not  so  frequently.     Children  and  women  breathe  more 
rapidly  than  men.     Exercise,  especially  fast  running,  quick- 
ens  the  respiratory  movements.     So,  also,  the  exhilarating 
affections —  cheerfulness  —  laughter  —  have  the  same  effect. 


EESP1KATION.  151 

On  the  ether  hand,  fatigue,  depression  of  spirit,  grief,  and 
anxiety  diminish  the  frequency  of  respiration. 

343.  The  lungs  of  a  man  of  average  size,  and  in  usual 
health,  when  at  rest,  when  neither  expanded  nor  contracted, 
will  hold  two  hundred  and  ninety  cubic  inches,  or  a  little 
less  than  a  gallon  of  air.   But,  when  distended  by  ordinary  in- 
spiration, they  receive  twenty  inches  more.    This  will  make 
three  hundred   and  ten  inches  when  full.      This  twenty 
inches  is  the  usual  extent  of  respiration.    This  is  the  amount 
of  air  which  the  lungs  need,  and  which  they  receive  at  every 
inspiration,  when  allowed  freedom  of  motion,  eighteen  times 
a  minute,  and  one  thousand  and  eighty  times  an  hour. 

344.  This  quantity  of  pure  air  is  not  merely  wanted  to  fill 
the  capacity  of  the  chest  and  lungs,  but  it  is  needed  for  the 
purification  of  the  blood.     Bearing  in  mi«d  that  the  blood 
receives  from  the  system  carbon  and  hydrogen  of  which  it 
must  be  relieved;    and    knowing   that  it  receives  with  the 
chyle  more  water  than  is  wanted ;  and  that,  when  these  are 
combined,  they  go  to  the  lungs  to  be  disburdened  of  their 
superfluous    and   noxious   elements;    it   is   natural  to   sup- 
pose that   the    amount  of  air  should  correspond    with  the 
quantity  of  these   matters,    which    are    thus  to  be  removed. 

345.  Then  in  order  that  the  air  may  meet  the  wants  of 
the  blood,  the  size  of  the  chest  corresponds  to  that  of  the 
body,  and  the  motions  of  the  ribs  and  the  expansion  of  the 
lungs  correspond  to  the  flow  of  the  blood.  This  one  would 
suppose  to  be  the  case  from  a  mere  general  view  of  the  har- 
monies of  nature;  for  the  Creator  makes  all  his  works  con- 
sistent one  with  another. 

346.  The  quantity  of  blood  in  the  whole  system  of  a  man 
of  average  size,  amounts  to  about  twenty-eight  pounds. 
(§  232,  p.  107.)  The  heart  beats  in  a  man  about  seventy-five 
times  a  minute,  and  forces  out  of  itself  about  two  ounces,  or 
half  a  gill,  at  each  pulsation  or  contraction  ;  and,  consequent- 
ly, in  one  minute,  more  than  nine  pints  of  blood  are  sent 
to  the  lungs  to  be  acted  upon  by  the  air.  In  the  same  time, 
twelve  pints  of  fresh  air  are  brought  into  the  lungs ;  arid 


152  PHYSIOLOGY    AND    HEALTH. 

the  amount  of  carbon  in  the  nine  pints  of  blood  corresponds 
very  nearly  with  the  capacity  of  the  twelve  pints  of  air  to 
carry  it  away. 


CHAPTER   XI. 

Air  spoiled  by  Loss  of  Oxygen  and  by  Carbonic  Acid  Gas.  —  Capaci- 
ty of  Air  to  receive  Vapor.  —  More  Air  saturated  by  Vapor  of 
Breath  in  cold  than  in  warm  Day.  —  Vapor  from  Skin  saturates 
some  Air.  —  Amount  of  insensible  Perspiration. —  Quantity  of  Air 
spoiled  by  Loss  of  Oxygen,  by  Carbonic  Acid,  and  by  Water. 

347.  BREATHING  air  once  destroys  or  weakens,  and,  par- 
tially at  least,  spoils,  for  the  purpose  of  respiration,  720  cubic 
inches  of  air  a  minute,  by  the  mere  consumption  or  use  of  its 
oxygen.     On  this  account,  we  need  about  one  half  a  cubic 
foot  of  air  every  minute.     When  the  air  goes  out  from  the 
lungs,  it  contains  about   four  or  five   per  cent,  of  carbonic 
acid  gas,  (§  302,  p.  136;)  .but  if  it  contains  more  than  three 
and  a  half  per  cent,  of  this  gas,  it  is  unfit  to  be  breathed 
again. 

348.  It  necessarily  follows,  then,  that  the  air  which  has 
been  once  breathed,  contains  about  two  and  a  half  times  this 
proportion,  and  therefore  the  quantity  of  this  injurious  gas 
that  is  the  product  of  one  respiration,  is  sufficient  to  corrupt 
nearly  opce  and  a  half  as  much  more.     The  quantity  which 
is  exhaled  in  one  minute  would  give  three  and  a  half  per 
cent,  to  1800  inches,  and  render  so  much  unfit  to  be  breathed 
again. 

349.  There  is  a  limit  to  the  power  of  the  air  to  take  up 
and  carry  away  the  watery  vapor  from  the  lungs,  and  this 
limit  differs  with  the  temperature.     When  the  air  is  cooled 
down  to  32°,  or  freezing  point,  a  cubic  foot  of  it  will  hold 
about  two  and  a  half  grains  of  water  in  solution.     When  it 
is  raised  up  to  65°,  which  is  usually  the  proper  temperature 
of  sitting-rooms,  it  will  hold  a  little  more  than  seven  grains ; 
and  at  90°,  which  is  very  nearly  the  temperature  of  the  air 


EESPIKATION.  153 

when  it  goes  out  from  the  lungs  it  will  hold  fifteen  grains. 
This  vapor  is  invisible,  and  generally  imperceptible.  But  if 
the  air  at  90°,  containing  fifteen  grains  in  a  cubic  foot,  be 
cooled  down  to  32°,  it  then  can  hold  only  two  and  a  half 
grains;  and  the  difference  between  these  quantities  —  twelve 
and  a  half  Drains  —  will  be  condensed  and  become  visible  in 

O 

the  form  of  water. 

350.  The  cloud  of  vapor  which  one  seems  to  expire  in  a 
cold  day,  is  caused  by  this  condensation.     If,  in  winter,  one 
or  more  persons  sit  in  a  room  sufficiently  warm  to  be  com- 
fortable, the  air  becomes  filled  with  pulmonary  vapor.     If 
the  temperature  of  the  room  is   the  same  throughout,  this 
vapor  is  imperceptible  to  the  eye ;  but  the  air  near  the  win- 
dows, if  these  are  not  double,  becomes  cooled  by  the  action 
of  the  outward  air,  and  then  this  vapor  rS  condensed,  and 
lodged   upon   the   glass   in   the  form  of  water.     If  the  air 
abroad  is  cooled  below  freezing  point,  this  condensed  vapor 
freezes  upon  the  windows,  and  the  glass   becomes  coated 
with  a  layer  of  ice.     So  we  usually  find  the  windows  of  our 
sleeping-chambers  covered  with  ice  from  this  cause,  in  the 
cold  mornings  of  winter. 

351.  The  whole  of  the  water  thrown  off  from  the  lungs  in 
this  state  of  vapor  amounts  to  about  seventeen  ounces  in  a 
day,*  which  will  make  five  grains  and  two  thirds  a  minute. 
This  will  saturate  nearly  one  half  a  foot  of  air  at  90° ;  but, 
as  air  usually  contains  about  one  grain  of  vapor  in  each 
cubic  foot,  it  can  absorb  so  much  less,  and  more  air  will  be 
saturated  with  the  pulmonary  vapor. 

352.  The    insensible   perspiration    is   another   and    very 
fruitful  source  of  moisture  in  the  air.     The  skin  is  a  very 
active  agent,  and  is  incessantly  throwing  off  watery  vapor 
from  its  surface.     When  this  runs  freely  in  drops,  it  is  called 
siceat,  arid  seems  to  be  very  abundant.     But  this  is  only  a 
small  part  of  the  whole  of  this  fluid,  which  is  thrown  off 
through  the  external  surface  ;  for  a  much  greater  quantity 
is  sent  off  in  an  invisible  form. 

*  Valentin  and  Dalton. 


154  PHYSIOLOGY    ASD    HEALTH. 

353.  The  quantity  of  this  insensible  perspiration  varies 
from  thirty  ounces  a  day  in  the  northern,  to  forty  ounces  a 
day  in  the  southern,  countries  of  Europe.     Carpenter  esti- 
mates it  to  be  thirty-three  ounces  in  England ;  this  is  eleven 
grains  a  minute;  others  give  a  much  higher  estimate.     Cruik- 
shank's  experiments  demonstrated  it  to  vary  from  twelve  to 
forty-five  grains  a  minute ;  and  he  assumes  the  mean,  from 
persons  of  both  sexes,  of  average  size,  and  in  good  health, 
to  be  twenty-three  grains  a  minute.     Taking  the  last  as  the 
standard,   and   adding  these  twenty-three  grains  to  the  five 
grains  and  two  thirds  of  vapor  thrown  out  from  the  lungs, 
we   have  enough  to  saturate  somewhat  more  than  two  feet 
of  air  with  moisture  ;  and,  so  much  air  being  saturated,  it 
can  take  no  more  vapor  from  the  lungs. 

354.  Thus  we  see  that,  in  these  three  ways,  the  air  loses 
its  power  of  relieving  the  blood  of  its  superfluous  carbon  and 
water,  and  is  thereby  rendered  unfit  for  the  work  of  respira- 
tion; —  first,   by  the   loss   of  its   oxygen,   in   each   minute, 
720  inches ;  secondly,  by  saturation  with  carbonic  acid  gas, 
1800  inches;    thirdly,   by  saturation   with  vapor    from   the 
lungs  and  skin,  3590  inches. 


CHAPTER   XII. 

Seven  to  ten  Feet  of  Air  spoiled  each  Minute.  —  Want  of  fresh  Air 
in  Houses,  but  not  provided.  —  Size  of  Parlors,  and  Number  of 
Occupants.  —  Small  Sleeping-Chambers.  —  Lodging-Rooms  in 
Boarding  Houses,  and  in  temporary  Houses.  —  Cabins  of  Steam 
and  Canal  Boats. 

355.  About  four  cubic  feet  of  air  being  rendered  by  each 
person  partially  or  entirely  useless  for  the  purpose  of  purifying 
the  blood  and  giving  it  new  life,  it  will,  of  course,  be  neces- 
sary that  we  have  so  much  new  and  fresh  air  supplied  every 
minute  for  each  one.  If  this,  after  having  been  once  breathed, 
or  saturated  with  vapor,  were  carried  immediately  away,  this 


RESPIRATION.  155 

quantity  would  be  sufficient ;  but,  as  the  corrupted  air  min- 
gles with  the  pure,  this  is  partially  corrupted ;  therefore  we 
need  a  larger  supply  to  support  respiration.  The  best  au- 
thorities on  the  subject  of  ventilation  consider  seven  feet  as 
the  least  that  should  be  supplied  to  each  person;  and  Dr. 
Reid  allows  ten  feet.  Taking  the  lowest  estimate,  seven  feet 
will  be  considered  as  necessary  for  the  maintenance  of  the 
healthy  respiration  of  each  person  in  each  minute  of  life. 

356.  If  we  always  dwelt  in  the  fields,  we  should   have 
fresh  air  enough,  without  any  effort  on  our  part.     But  when 
we  live  in  closed  houses,  it  becomes  a  question  whether  we 
are  thus  supplied,  and  the  wants  of  nature  are  satisfied ;  and, 
if  our  rooms  are  made  air-tight,  then  it  is  necessary  to  deter- 
mine whether  they  contain  air  sufficient  for  the  consumption 
of  all  that  inhabit  them,  as  long  as  they  sfay  there.     If  this 
be  not  the  case,  then  it  is  necessary  to  find  some  means  to 
carry  off  the  foul  air  as  fast  as  it  is  rendered  so  by  respira- 
tion, and  to  bring  in  a  new  supply  from  abroad  to  take  its 
place. 

357.  A  continued  supply  of  fresh  air  for  all  inhabited 
rooms   is  as  necessary  as  a  continued  supply  of  heat  in  cold 
weather.     And  yet  provision  is  not  usually  and  intentionally 
made  to  meet  this  necessity  in  the  arrangements  of  our  dwell- 
ings and  our  public  rooms.     The  architect  and  the  builder 
provide  carefully  for  warmth,  but  they  generally  make  little 
or  no  provision  for  respiration.     Fortunately,  the  imperfec- 
tion of  the  builder's  work  obviates,  in  some  small  degree, 
and  generally  prevents,  the  immediately    destructive  conse- 
quence of  the  defects  of  the  architect's  plans.     It  is  difficult 
—  almost  impossible  —  to  make  a  room  so  tight  that  no  air 
can  force  itself  into    it,  when   the   internal    atmosphere  is 
heated,  or  vitiated  by  respiration. 

358.  A  room  sixteen  feet  square,  and  nine  feet  high,  will 
contain  2304  cubic  feet.     This  will  be   sufficient  for   four 
persons  less  than  an  hour  and  a  half  for  ordinary  day  pur- 
poses.    This  room,   though   not  so  large  as  some  that  are 
inhabited  by  day  or  by  night,  is  yet  as  large  as  most,  and 


156  PHYSIOLOGY    AND   HEALTH. 

much  larger  than  many  rooms  so  occupied.  It  is  esteemed  a 
proper  economy  to  have  small  and  tight  parlors  and  sitting- 
rooms,  for  the  occupation  of  the  families  during  the  day  and 
evening.  On  an  average  these  do  not  probably  contain 
more  than  1700  feet.  If  only  four  persons  inhabit  one 
of  these,  they  would  have  air  sufficient  for  less  than  one  hour. 

359.  It  is   considered,  by  many,  a  prudent   architectural 
design,  to  have  many  and  small  sleeping-chambers.      Room 
for  the  bed  and  wardrobe,  and  for  convenient  dressing,  is  all 
that  is  thought  absolutely  necessary.     At  least,  the  plan  of  a 
good  dwelling  generally  includes  a  portion  of  these  narrow 
chambers.     Many  of  these  will  not  contain  more  than  500 
cubic   feet ;    and  in  such,  two  grown  persons,  often   more 
than   two   children,  sleep   during   the   night.      Here   is    air 
enough  to  last  two  persons  a  little  more  than  half  an  hour. 

360.  In  public  boarding-houses,  in  some  taverns,  and  in 
the  houses  where  the  operatives  of  factories  are  boarded,  it 
is  an  object  to  lodge  the  family  as  cheaply  as  possible.     Con- 
sequently, the  lodging-rooms  are  often  made  as  small,  or  to 
hold  as  many  sleepers,  as  they  can.     Oftentimes  these  lodgers 
are  so  closely  crowded,  as  to  have  hardly  air  enough  for  half 
an  hour's  respiration.     At  one  of  our  large  manufacturing 
establishments,  eight,  sleep  in  one  chamber  containing  2574 
feet;    in  several  other  chambers,  two  have  262^-  feet,  four 
have  1800  feet,  six  have  973£  feet,  four  have  686£  feet,  for 
a  night's  respiration.     These  rooms  contain  air  enough  to 
supply  their  occupants  from  twenty-five  to  sixty-six  minutes. 

361.  This  close  crowding  of  sleeping-chambers  is  carried 
to  the  greatest  extent  in  some  of  the  lodging-houses  built  for 
temporary  usa  on  some  of  the  railroads,  and  other  public 
works.     I  have  the  measure  of  one  of  these  chambers.     The 
room  was  in  the  attic,  —  sixteen  feet  long,  and  fourteen  feet 
wide.     The  height  was  six  feet  ten  inches  in  the  middle,  but 
the  roof  met  the  floor  at  the  sides,  so  that  the  average  height 
of  the  room  was  three  feet  five  inches,  and  the  whole  cubic 
contents   of  this   chamber  were   765    feet.     There  were  no 
means  whatever  provided  for  the  ventilation  of  this  room. 


RESPIRATION.  157 

There  was  neither  window  nor  door.  The  only  opening 
made  into  the  chamber  was  a  small  hole  in  the  floor,  through 
which  the  sleepers  ascended  from  the  room  below.  This 
lower  room  was  not  ventilated  much  better.  It  had  less 
than  1400  cubic  feet  of  space ;  and  there  nineteen  persona 
boarded  or  lived  in  the  day,  and  five  slept  at  night,  and  there 
all  the  operations  of  cooking,  eating,  and  washing  were 
carried  on. 

362.  In  this  chamber,  with  less  than  800  feet  of  air,  four- 
teen  men  slept  through  the  night ;  and  for  eight  hours  these 
men  breathed  over  and  over  the  air  from  each  other's  lungs, 
in  the  vain  attempt  to  purify  their  blood,  and   refresh   their 
frames,  and   invigorate  themselves  for  the  next  day's  labor. 
Here  was  air  provided  sufficient  to  last  them  less  than  nine 
minutes,  and  yet  it  was  required  to  last  them  480  minutes ; 
and  in  this,  as  well  as  in  other  crowded  chambers,  nothing 
but  the  undesigned  ventilation  through  the  crevices  of  the 
imperfect  carpentry,  saved   these  sleeping  occupants    from 
suffocation. 

363.  The  crowded  state  of  the  cabins  of  steamboats,  in 
which  the  sleeping  apartments  are  below  decks,  and  of  the 
canal  boats  at  night,  leaves  less  air  for  respiration  than  even 
these  rooms.     Not  unfrequently,  fifty  or  even  sixty  persons 
sleep  in  the  narrow  cabin  of  a  canal  boat,  which  contains 
no  more  space  than  some  of  the  airy  chambers  where  only 
two  cautious  people  would  usually  spend  the  night. 


CHAPTER  XIII. 

Crowded  Workshops.  —  Chambers.  —  Public  Halls.  —  Churches.  — 
School-Rooms.  —  School-Rooms  rilled  with  foul  Air.  —  Habit  of 
breathing  each  other's  Expirations.  —  Foul  Air  offensive.  —  Ven- 
tilation. 

364.    SOME  of  the  trades  require  a  very  small  space  for 
iheir  operations.     The  shops  in  which  these  are  carried  on 
14 


158  PHYSIOLOGY    ASD    HEAiTH. 

are  therefore  constructed  in  reference  rather  to  the  conve- 
nience of  the  work,  and  the  economy  of  heating  them,  than 
to  the  health  of  the  workmen.  Consequently,  these  men  are 
sometimes  so  crowded  and  confined  as  to  have  insufficient 
air  for  respiration.  In  a  room  ten  feet  square,  and  eight 
feet  high,  with  800  feet  of  air,  six  and  sometimes  eight  men 
can  work,  without  interfering  with  each  other ;  and  this  is 
thought  good  accommodation. 

365.  Family  rooms,  lodging-chambers,  cabins,  and  shops 
are  not  the  only  places  where  men  and  women   gather  in 
numbers  beyond  the  capacity  of  the   air  to  support  their 
healthy  respiration.     Public  rooms,  lecture-rooms,  churches, 
concert   halls,  and,  above   all,  school-rooms   generally,   are 
badly  ventilated.     They  are  not  supplied  with  air  sufficient 
for  the  ordinary  numbers,  and  still  less  for  the  occasional 
crowds,  that  meet  in  them.     The  general  plan  of  these  is  to 
hold  many  persons ;   and  the  idea  of  the  architect  is  to  so 
arrange  the  seats,  that  the  greatest  possible  number  may  be 
gathered  into  a  given  space. 

366.  A  part  of  these  pages  on  respiration  were  read  as  a 
lecture  before  an  associated  audience,  which  assembled  in  a 
hall  forty-seven  feet  long,  thirty-seven  feet  wide,  and  nine 
feet  high,  measuring  15,650  cubic  feet.     This  room  is  made 
to  hold  five  hundred  persons  when  full ;  and  usually   from 
three  to  four  hundred  meet  there.     In  the  former  case,  there 
are  thirty-one  feet,  and  in  the  latter  thirty-nine  to  fifty-two 
feet  of  ajr  for  a  person.     The  sittings  of  this  society  vary 
from  one  to  three  hours. 

367.  A  church  which  has  been  recently  built  has   one 
hundred  and  eighty-three  feet  of  air  for  a  person,  in  an  av- 
erage audience,  and  one  hundred  and  thirty-six  feet  when 
crowded.     Another  has  from  seventy-five  to  ninety-nine  feet 
of  air  for  each  of  the  people,  according  to  their  numbers. 
Many  other    churches   afford    about  the  same  proportion  of 
air  to  their  occupants.     I  have  not  their  exact  measurement, 
as  of  these  above  stated  ;  but  the  foulness  of  the  air  which 
one  perceives  on  entering  them  late  in  the  forenoon,  or  in  the 


RESPIRATION.  159 

afternoon,  too  plainly  shows    that  they  have   not  sufficient 
ventilation. 

368.  In   times   of  great  excitement,  the   crowds   in  the 
churches  or  halls  are  more  dense  even  than  thes§.     It  is  esti- 
mated by  those  observant  of  the  matter,  that,  in  the  closest 
crowds,  a  man  standing  will    not   occupy    more    than    two 
square  feet  of  surface ;   and  therefore  a  room  can  hold  half 
as  many  as  there  are  square  feet  of  floor.     This  would  give 
twice  as  many  cubic  feet  of  air  as  the  height  of  the  room 
above  the  heads  of  the  people.     I  have   stood    in    Faneuil 
Hall  when  each  man  had  very  little  more  space  for  air  than 
that  which  was  over  his  head  to  the  ceiling  above. 

369.  School-houses    seem  to   be    as  imperfectly  supplied 
with  air  as  public  halls.     It  is  rare  that  one  enters  a  school- 
room from  the  fresh  air  abroad,  after  the  scholars  have  been 
in  a  few  minutes,  without   perceiving  the   foulness  of  the 
atmosphere  within.     A  room  thirty  feet  square  is  ordinarily 
supposed  to  be  large  enough  for  eighty  or  ninety  children  ; 
and,  if  the  room  be  nine  feet  high,  this  will  allow  eighty  or 
ninety  feet  of  air  for  every  child,  which  is  sufficient  for  their 
respiration  twelve  or  thirteen  minutes.     The    air  of    these 
rooms  becomes  loaded  with  carbonic  acid  gas,  with  the  foul 
secretions  of  the  lungs,  and  the  excretions  of  the  skin.     It 
is  offensive,  so  much  so  as  sometimes  to  produce  sickness 
and  faintness  in  those  who  enter  from  the  external  air. 

370.  But  "  not  the  least  remarkable  example  of  the  power 
of  habit  is  its  reconciling  us  to  practices  which,  but  for  its 
influence,  would  be  considered  noxious  and  disgusting.     We 
instinctively  shun  approach  to  the  dirty,  the  squalid,  and  the 
diseased,  and  use  no  garment  that  may  have  been  worn  by 
another.     We  open  sewers  for  matters  that  offend  the  sight 
or  the  smell,  and  contaminate  the  air.     We  carefully  remove 
impurities  from  what  we  eat  and  drink,  filter  turbid  water, 
and    fastidiously  avoid  drinking  from  a  cup  that  may  have 
been  pressed  to  the  lips  of  a  friend.     On  the  other  hand,  we 
resort  to  places  of  assembly,  and  draw  into  our  mouths  air 
loaded  with  effluvia  from  the  lungs,  skin,  and  clothing  of 


160  PHYSIOLOGY    AND    HEALTH. 

every  individual  in  the  promiscuous  crowd  —  exhalations 
offensive,  to  a  certain  extent,  from  the  most  healthy  individ- 
uals ;  but  when  arising  from  a  living  mass  of  skin  and  lungs, 
in  all  stages  of  evaporation,  disease,  and  putridity,  prevented 
by  the  walls  and  ceiling  from  escaping,  they  are,  when  thus 
concentrated,  in  the  .highest  degree  deleterious  and  loath- 
some." * 

371.  When   one   enters    any  rooms   thus    crowded,  and 
inhales  the  air  thus  exhausted  and  corrupted,  he  perceives, 
at  once,  an  offensive  and  oppressive  smell,  and  there  comes 
a  feeling  of  suffocation  about  his  throat  and  chest,  followed 
by  some  degree  of  faintness.     But  those  who  live  in  it,  hav- 
ing by  degrees  become  accustomed  to  it,  do  not  perceive  the 
smell ;  the  sensibility  of  their  lungs  and  nostrils  is  blunted ; 
they  are  not  offended  with  the  foul  odor  of  the  atmosphere; 
yet  their  lungs  do  not  find  the  oxygen  to  purify  the  blood, 
and  cannot  perform  their  work  successfully.     They  are  not 
relieved  of  the  waste  of  dead  atoms  of  flesh  within  them. 

372.  It  is  evident  that  unless  there  is  some  way  of  re- 
moving the  respired  and  foul  air  from  these  rooms,  arid  of 
replacing  it  with  new  and  fresh  air  from  abroad,  the  work  of 
respiration  cannot  be  carried  on  as  it  should  be,  the  blood 
cannot  be  purified  of  its  dead  particles,  and  the  system  can- 
not be  nourished  with  life  and  energy ;  and  then  the  con- 
ditions which  nature  established  for  our    existence   cannot 
be  fulfilled. 

373.  Ventilation,  or  the  means  of  supplying  fresh  air  to 
every  inhabited  room,  every  parlor,  sleeping  chamber,  school- 
house,  public  hall,  church,  or  shop,  in  which  people  live,  is, 
then,  as  necessary  as  the  supply  of  food.     After  the  air  already 
in  the  room  is  consumed  or  vitiated,  it  must  be  removed,  and 
as  much  brought  in  every  minute  as  is  used  or  spoiled.     There 
must,  then,  be  two  constant  currents ;  one  outward,  carrying 
off  the  foul  air,  and  the  other  inward,  bringing  in  pure  air. 
The  outward  current  may  pass  upward  through  the  chimney, 

*  Bernan,  Art  and  History  of  Warming  and  Ventilation,  Vol.  II.  p.  313, 


RESPIRATION.  161 

or  through  the  crevices  in  the  upper  part  of  the  ceiling,  or 
through  a  passage-way  provided  for  the  purpose.  The  in- 
ward current  more  commonly  comes  through  the  uninten- 
tional crevices  which  the  skill  of  the  architect  and  mechanic 
seldom  entirely  prevents,  and  which  admit  air  sufficient  to 
save  the  occupants  from  the  death  of  the  Black  Hole,  but 
not  enough  to  save  them  from  some  sickness,  or  faintness, 
or  certainly  some  depression  of  life.  As  those  crevices  are 
inadequate  to  supply  the  air  that  is  needed  to  sustain  the  ful- 
ness of  life,  every  room  that  is  inhabited,  and  especially  every 
hall  that  is  filled  with  people,  and  every  school-room,  should 
be  provided  with  means  of  ventilation  sufficient  to  adinit  and 
to  carry  away  at  least  seven  feet  of  air  a  minute  for  each  oc- 
cupant. For  this  purpose,  a  school-room,  with  forty  persons, 
should  have  a  ventilator  a  foot  square,  through  vbich  the  air 
should  move  upward  at  the  rate  of  two  hundred  ond  eighty 
feet  a  minute,  and  as  much  fresh  air  should  be  received.*  In 
ordinary  circumstances,  air  cannot  be  compressed  ;  no  more 
can  be  received  into  a  room  than  is  carried  out.  It  is  there- 
fore useless  to  provide  means  for  the  admission  of  fresh  air 
by  a  furnace  or  otherwise,  unless  there  be  some  avenue, 
either  accidental  or  designed,  for  the  foul  air  to  escape. 
Nor  can  a  room  be  emptied  of  air ;  none  will  go  out  unless 
as  much  comes  in.  A  ventilator  will  not,  then,  carry  away 
the  foul  air,  unless  there  be  .some  place  accidentally  left,  or 
especially  provided,  for  the  admission  of  other  air  to  take 
its  place. t 

*  This  current  of  air  upward  is  accelerated  by  placing  a  large  burning  lamp 
in  the  flue  of  the  ventilator.  In  most  school-houses,  a  larger  ventilator  — 
one  measuring  four  or  more  square  feet  —  will  be  better,  and  will  carry  off 
the  foul  air  sufficiently  with  a  slower  current 

t  "  Experiments  have  been  made,  in  a  room  prepared  expressly  for  the  pur- 
pose 5  and  in  the  House  of  Commons,  every  day  of  the  session,  for  two  years; 
and  the  results  show  that  it  was  rare  to  meet  with  a  person  who  was  not 
sensible  of  the  deterioration  of  the  air  when  supplied  with  less  than  ten  cubic 
feet  per  minute." — Wyman  on  Ventilation. 

For  the  best  practicable  methods  of  ventilation  of  dwelling-houses,  school- 
rooms,  and  public  halls,  Dr.  Wyman's  valuable  work  can  be  advantageously 
consulted. 

14* 


162  PHYSIOLOGY    AND    HEALTH. 


CHAPTER   XIV. 

Connection  between  Fulness  of  Life  and  Respiration.  —  Hybernating 
Animals  stupid.  —  Man  is  lively  or  dull  in  Ratio  of  Respiration.  — 
Consumptive  Persons  have  less  Energy  of  Life.  —  Diminution  of 
Air  and  Respiration  lowers  Life.  —  Lodgers  in  unventilated  Cham- 
bers unrefreshed  in  Morning. 

374.  Nature    has    connected    a  fulness,    buoyancy,    and 
energy  of  life  with    the    amount  of  respiration.     Reptiles, 
snakes,    frogs,    have    a    small    respiratory    apparatus;    they 
breathe  but  little,  and  are  dull,  heavy,  and  inactive.     They 
have  comparatively  little  muscular  energy,  and  little  nervous 
power.     As  we  ascend  in  the  scale  of  animals,  we  find  the 
correspondence    between    the    activity    of  their   respiratory 
functions  and  their  general  vital  energy  to  be    more    and 
more  manifest.     Birds  have  more  life  and  muscular  power 
than  other  animals,  and  they  have  a  fuller  development  of 
their  respiratory  apparatus,  and  breathe  a  freer  air.     Man, 
also,  has  a  larger  preparation  for  breathing,  and    more   ener- 
gy of  nervous  and  of  muscular  life. 

375.  The  hybernating  animals  retire  to  holes  and    cav- 
erns in  winter;    and  there  they  spend  the  cold  season  in  a 
torpid,  insensible,  almost  lifeless  state.     But,  in  the  spring, 
they  come  out  with  new  life  aryi  activity.     In  the  dormant 
state,  the  hedgehog  breathes  only   four  or  five  times,   and 
the  dormouse  eight  or  nine  times,  a  minute,  and  both  with 
so  little  motion  as  to  be  scarcely  perceptible.     While  their 
respiration  is  thus  feeble,  all  their  voluntary  functions,  their 
power   of  motion,   and  their  sensations,  seem    entirely  sus- 
pended, and  their  vital  energies  reduced  to  the  lowest  point 
consistent  with  the  bare  continuance  of  life. 

376.  But  the  warm  weather  of  spring  gives  them  a  ne\v 
life;  then  the  lungs  again  expand,  and  work  with  their  ac- 
customed activity ;  the  blood  circulates  freely ;  the  old  par- 
ticles are  taken  away,  and  new  ones  supply  their  places,  and 
respiration  carries  otf  the  offensive  matters,  and  the  whole 


RESPIRATION.  163 

animal  is  revived  into  buoyancy  and  energy.  In  these  ani- 
mals, while  respiration  is  low,  life  is  low ;  and,  on  the  con- 
trary, while  respiration  is  active,  life  is  in  the  same  condition. 
A  similar  relation  between  the  amount  of  respiration  and 
the  fulness  and  activity  of  life  is  shown  in  the  various  races 
of  animals.  "  The  development  of  their  locomotive  powers, 
and  the  degree  of  heat  maintained  in  their  systems,  will  be 
found  peculiarly  connected  with  the  activity  of  respiration."  * 
Those  which  breathe  most  are  the  most  vigorous,  lively,  and 
active,  while  those  which  breathe  least  are  the  most  sluggish, 
stupid,  and  feeble. 

377.  The  same  law  holds  good  for  the  different  individu- 
als of  any  class,  as  well  as  for  the  various  races  of  animals. 
There  is  a  manifest  connection  between  any  man's  fulness 
and  energy  of  life  and  the  development  and  free  use  of  his 
respiratory  organs.     Wherever  the  lungs  are  imperfect,  or 
air  insufficiently  supplied,  there  is  a  lower   life,  a  feebler 
power  of  locomotion,  less  muscular  energy,  a  duller  nervous 
system,  a  more  inactive  brain. 

378.  These  effects  are  not  always  noticed  and  referred  to 
their  true  causes,  yet  they  are  none  the  less  certain.     In 
persons  suffering  from  consumption,  the  lungs  are  more  or 
less  rilled  with  tubercles  and  abscesses ;  the  air-vessels  are,  to 
the  same  extent,  closed,  so  that  the  air    cannot  penetrate 
them,  and  reach  the  blood,  to  purify  it.     These  men  are  not 
well  nourished,  for  want  of  pure  blood,   and  therefore  they 
waste   away ;  their  muscles  grow  thin  and  weak,  arid  their 
buoyancy  of  life  is  extinguished.     Their  lungs  become  filled 
more  and  more  as  the  disease  progresses ;  and,  at  last,  when 
respiration  can  no  longer  be  carried  on  with  sufficient  power 
to  effect  its  due  purposes,  they  sink  in  death. 

379.  Whatever  may  be  the  cause  that  prevents  the  lungs 
from  receiving  a  full  and  requisite  quantity  of  air,  the  result 
is  the  same  —  a  lower  degree  of  life.     Whether  the  chest  be 
originally  small  in  proportion  to  the  size-  of  the  body,  or 

*  Carpenter's  Comparative  Physiology. 


164  P1TTSIOLOGY    AND    HEALTH. 

made  so  by  artificial  means,  or  -whether  it  be  encased  so  as 
to  prevent  its  natural  expansion  for  the  admission  of  air, 
there  necessarily  follows  the  same  diminution  of  energy  in 
the  performance  of  the  function  of  respiration. 

380.  The  effect  of  imperfect  respiration  upon  the  blood, 
and  upon  the  energy  of  life,  is  the  same,  whether  it  come 
from  want  of  room  in  the  lungs  to  receive  the  air,  or  from 
want   of  oxygen   in   it.     Those   who   breathe   impure    and 
corrupted  air,  and  those  who  live  in  small  and  ill-ventilated 
rooms,  show  the  same  languor  and  feebleness,  the  same  want 
of  muscular  power  and  buoyancy  of  spirit,  as  those  who  are 
suffering  from  consumption,  or  who  have  deformed  or  dimin- 
utive chests. 

381.  The  object  of  sleep  is  to  restore  the  exhausted  ener- 
gies, and  give  us  new  life  for  labor  in  the  morning.     But 
for  want  of  sufficiency  of  air,  this  balmy  restorer  often  fails 
in  some  measure  of  fulfilling  its  purposes ;  and,  in  some  in- 
stances, it  comes  very  far  short  of  it.     In  small  and  crowded 
chambers,  the  sleep  is  not  sound   and  refreshing,   and  the 
sleeper  awakes  in  the  morning  unrefreshed,  indisposed  to  get 
up,  and  irresolute  in  regard  to  labor. 

382.  The  laborers  who  slept  in  the  narrow  attic  of  the 
shanty  (§§  361,  362,  pp.  156,  157)    assured  me  that  they 
awoke  in  the  morning  almost  as  weary  as  when  they  went  to 
their  chamber ;  they  felt  no  vigor  nor  elasticity ;  they  were 
not  refreshed  by  their  sleep ;  they  felt  a  slight  nausea,  and  a 
sinking  about  the  heart,  and  some  headache,  after  they  rose ; 
and  they  ran,  as  soon  as  possible,  out  of  doors,  to  breathe 
the  fresh  air.     After  being  in  the  open  air  a  while,  they  re- 
covered their  comfortable  feelings,  and  then  had  some  appe- 
tite for  their  breakfast.     Even  then  they  had  not  the  muscular 
vigor,  nor  the  power  for  labor,  which  they  would  have  had 
if  they  had  been  well  supplied  with  air  during  their  sleep. 
It  is  a  mistaken  economy  to  give  laborers,  or  others  who  aro 
expected  to  use  their  powers,  such  small  lodging  apartments. 
I  have  felt  the  same  languor  and  sickness  after  sleeping  in 
the  cabins  of  boats,  and  have  seen  the  passengers  rush  to  the 


RESPIRATION.  165 

deck  in  the  morning,  even  in  cold  and  stormy  weather,  to 
inhale  the  fresh  air,  and  remove  the  oppression,  and  recover 
themselves  from  the  weariness  of  their  night's  lodging. 


CHAPTER   XV. 

Crowded  Audiences  uneasy  and  impatient.  —  Children  in  unventi- 
lated  School-rooms  uneasy  and  dull.  —  Deficiency  of  pure  Air  de- 
preciates, and  total  Want  of  it  extinguishes  Life. —  Breathing  Car- 
bonic Acid  Gas.  —  Drowning.  —  Breathing  impure  Air  impairs 
Constitution.  —  Consumption  among  Females. 

383.  A  CROWDED  audience  in  a  lecture-room  or  concert- 
hall,  after  a  while,  become  weary  and  uneasy,  and  indiffer- 
ent to  the  lecture  or  the  music  before  them,  although  the  one 
may  still  be  as  interesting,  and  the  other  as  exquisite,  as  in 
the  beginning.     Their  senses  grow  dull ;  they  neither  under- 
stand the  arguments  of  the  speaker  so  readily,  nor  enjoy  the 
harmonies  of  the  music  so  keenly ;  and  yet  they  are  more  im- 
patient of  mistakes  and  imperfections.     Some  complain  that 
they  never  return  from  such  assemblies  without  a  headache. 
The  weariness,  the  restlessness,  the  impatience,  and  the  pain, 
all  arise  from  one  and  the  same  cause  —  the  foulness  of  the 
air.     For  want  of  oxygen,  the  blood  is  not  purified ;  then 
impure  blood  is  sent  to  the  muscles,  and  cannot  strengthen 
them  to  support  the  body ;  the  same  is  sent  to  the  brain,  and 
irritates  it,  and  disturbs  the  nervous  system. 

384.  After  children  have  sat  in  crowded  school  rooms  for 
some  time  they  grow  dull  and  heavy.     Their  blood  is  not 
then  relieved  of  its  carbon  and  hydrogen :  impure  blood  is 
sent  back  to  the  heart ;   and  thence  it  is  sent  again,  with  all 
its  imperfections,  to  the  whole  body.     The  brain,  being  fed 
with  this  corrupted  and  corrupting  blood,  instead  of  being 
enlivened,  is  made  inactive  and  heavy.     It  then  works  lan- 
guidly, or  refuses  to  work  at  all.     The  children  become  un- 
easy,   restless,   and   oftentimes   sleepy;    they    are  averse  to 


100  PHYSIOLOGY    AND    HEALTH. 

mental  labor,  for  it  is  difficult  for  them  to  fix  their  attention 
upon  their  studies;  and  they  are  fatigued  with  the  ineffectual 
attempts  to  learn  that  which  at  other  times  is  easy.  But  the 
moment  they  are  dismissed,  they  run  eagerly  from  the  im- 
pure air  of  the  room  to  the  pure  atmosphere  abroad,  and 
then  feel  a  return  of  life,  and  even  a  glow  of  exhilaration. 

385.  Whenever,  in  these  and  other  ways,  the  lungs  are  not 
supplied  with  a  sufficiency  of  pure  air  or  oxygen,  life  is  de- 
preciated, and  this  depreciation  is  in  proportion  to  the  foul- 
ness of  the  air.     If  men  dwell  in  rooms  that  are  perfectly  air- 
tight, so  that  no  fresh  air  can  be  admitted,  all  the  oxygen  is 
soon  consumed,  and  then  their  blood  can  be  relieved  of  no 
more  of  its   burden  of  dead   atoms,   and  the  vital   powers, 
not  being    sustained,  sink,  and  life  is  as  effectually  extin- 
guished as  it  would  be  if  they  were  buried  in  the  water.     In 
this  manner,  one  hundred  and  twenty-three  men  died  in  the 
Black  Hole  of  Calcutta.*     The  difference  between  the  faint- 
ness  and  languor  of  a  crowded  room  and  the  death  in  the 
Black  Hole  is  a  difference  only  in  degree,  but  not  in  kind; 
and  it  is  only  by  step  after  .step,  in  the  same  course  of  cor- 
rupting atmosphere  and  depreciating  life,  that  our  children 
in  the  unventilated    school-rooms,  and  our  sleepers  in  the 
small  chambers,  and  our  audiences  in  crowded  lecture-rooms, 
might  go  from   the  inconvenience   they  there   feel   to   the 
death  from  which  they  shall  awake  no  more. 

386.  If  breathing  air  loaded  with  more  than  three  and  a 
half  per  cent,  of  carbonic  acid  gas  be  injurious,  the  breath- 
ing this  gas  in  its  pure  state  is  destructive.     This  gas  is 
heavier  than  the  air,  (§  295,  p.  134,)  and  therefore  it  falls  to 
the  bottom  of  a  vessel  or  room,  like  water.     Hence  it  is  un- 
safe for  a  living  creature  to  go  to  the  bottom  of  wells  and  vats 
that  contain  it.     Fire  will  not  burn  in  this  gas.     Workmen, 

*  One  hundred  and  forty-six  persons  were  shut  up  in  a  room,  called  tiie 
Black  Hole  of  Calcutta,  on  the  night  of  the  20th  of  June,  1756.  This  room 
was  eighteen  feet  square,  and  eighteen  feet  high,  "  open  only  by  two  windows, 
strongly  barred,  from  which  they  could  scarcely  receive  the  least  circulation 
of  air."  "  \t  the  dawn  of  day,  only  twenty-three  persons  remained  alive  out 
of  one  hundred  and  forty-six." 


RESPIRATION.  167 

when  they  wish  to  enter  a  well  or  vat  where  they  suspect 
its  presence,  first  sink  a  lighted  candle  down.  If  it  burns, 
there  is  air,  and  it  is  safe  for  them  to  descend ;  but,  if  the 
candle  is  extinguished,  there  is  no  air  but  carbonic  acid 
gas ;  they  cannot  go  down  in  safety.  For  want  of  this  pre- 
caution, some  have  been  suffocated,  and  even  lost  their  lives. 

387.  Probably  more  have   perished  from   breathing    the 
fumes  of  charcoal  than  from  breathing  any  other  gas.     A 
pan  of  coals  is  sometimes  left  burning  in  a  small  bed-room, 
which  has  no  open  fireplace,  while  some  one  sleeps  on  the  bed. 
The  gas  given  out  falls  to  the  floor,  and  fills  the  bottom  of 
the  room,  rising  as  fast  as  it  is  produced,  until  it  reaches  the 
sleeper's  head.     At  first,  he  suffers  -difficulty  of  breathing, 
violent  pulsations  of  the  heart,  which  are  soon  followed  by  a 
partial  and  almost  entire  suspension  of  th€  respiration  and 
of  the  circulation  of  the  blood.     Then  the  organs  of  sense 
lose  their  power,  the  sensibility  is  destroyed,  the  prostration 
is  extreme,  and  the  want  of  power  of  motion  so  complete 
that  the  sufferer  seems  dead.     If  removed,  he  may  possibly 
be  restored ;  but,  if  he  remains  in  this  gas,  destruction  of  life 
follows  as  surely  as  if  the  sleeper  were  overwhelmed  with 
water. 

388.  Drowning  produces  death,  not,  as  is  commonly  sup- 
posed, by  filling  the  lungs  with  water,  but  because  the  water 
prevents  the  access  of  air  to  the  respiratory  organs,  and  tho 
sufferer  dies  from  suffocation. 

389.  The  effects  of  limited  respiration,  and  of  breathing 
impure  air,  have  thus  far  been  considered  only  in  the  imme- 
diate depreciation  of  life,  or  the  production  of  death,  by  the 
mere   deficiency  of  pure,    well-oxygenated    air. "   But  often 
injurious    and    even    fatal    consequences    afterward    come. 
Some  of  the  survivors  of  the  Black  Hole  were  seized  with 
putrid    fever,  and  subsequently  died.     Those  .who   breathe 
charcoal  gas  are  for  some  time  drowsy,  and  are  apt  to  fall 
into  a  deep  sleep,  or  lethargy,  from  which  it  is  difficult  to 
rouse  them ;   and  those  who  live  in  close  rooms  have   less 
mental   and   bodily  activity,  less  sprightliness   and  energy, 


1C8  PHYSIOLOGY   AND   HEALTH. 

less  power  to  sustain  themselves  under  the  exposures  of  life, 
and  less  strength  to  resist  the  causes  or  the  attacks  of 
disease. 

390.  Consumption  is  more  frequent  among  females  than 
among  males.  The  deaths  from  this  disease  in  Massachu- 
setts, during  the  registered  years  1845  to  1863,  were,  of 
males,  32,512;  females,  44,091.  And  in  England,  in  the 
ten  years  ending  with  1860,  there  were,  of  males,  239,305  ; 
females,  269,318.*  This  shows  that  the  mortality  from  this 
cause  was,  in  these  years,  in  Massachusetts,  25'5  per  cent., 
and  in  England,  7'5  per  cent.,  greater  among  the  females 
than  among  the  males  in  proportion  to  the  population  of 
each  sex  in  these  countries.  Dr.  Farr  says,  "  The  higher 
mortality  of  English  women  by  consumption  may  be  as- 
cribed partly  to  the  in-door  life  which  they  lead,  and  partly 
to  the  compression,  preventing  the  expansion  of  the  chest, 
by  costume.  In  both  ways  they  are  deprived  of  free 
draughts  of  vital  air,  and  the  altered  blood  deposits  tuber- 
culous matter  with  a  fatal,  unnatural  facility."  f 


CHAPTER  XVI. 

Lower  Animals  can  bear  Privation  of  Air  longer  than  higher.  — 
Some  Men,  by  Practice,  can  bear  this  longer  than  others.  —  All 
Animals  need  Air.  —  Air  covers  all  the  Earth.  —  Animals  con- 
sume Oxygen,  and  give  out  Carbonic  Acid  Gas. —  Vegetables  use 
Carbonic  Acid  Gas,  and  give  out  Oxygen. 

391.  IF  a  mouse  or  rabbit  be  placed  in  the  exhausted 
receiver  of  an  air-pump,  it  will  die  in  less  than  a  minute ; 
and  a  bird,  which  needs  more  air  and  that  more  frequently, 
could  not  survive  this  privation  more  than  half  a  minute. 
But  the  lower  animals,  which  have  less  energy  of  life,  endure 
this  much  longer.  Reptiles,  serpents,  frogs,  &/c.,  will  live  a 
considerable  time  in  a  vacuum,  or  in  such  gases  as  cannot 

*  Supplement  to  Registrar-General's  25th  Report,  p.  2. 
t  Registrar-Greneral's  2d  Report,  p.  73. 


RESPIRATION.  169 

be  respired ;  a  tortoise  lived  twenty-four  to  thirty-six  hours, 
and  frogs  lived  near  an  hour  when  placed  in  oil,  while  in- 
sects died  immediately,  if  placed  in  the  same  fluid.  Fishes 
die  if  the  water  be  boiled  and  the  air  excluded ;  yet  gold 
fishes  have  lived  in  water  thus  prepared  one  hour  and  forty 
minutes. 

392.  But  if  a  man  be^leprived  of  air,  or  of  the  power  of 
admitting  it  to  the  chest,  the  circulation  of  his  blood  will 
generally  cease  within  ten  minutes,  and  his  power  of  motion 
within  five,  often  within  three  minutes.     Yet  some  men,  by 
long  practice,  acquire  a  power  of  suspending  their  breath  for 
this   period,  without  suffering  any   apparent  loss  of  power. 
The  divers  of  Ceylon  are  in  the  habit  of  remaining  under 
water  three,  four,  or  even  five  minutes,  in  search  of  pearls ; 
and,  when  they  come  up,  they  seem  wearfed,  but  not  ex- 
hausted.* 

393.  This  necessity  of  good  air  is  imposed  upon  all  the 
animated  creation,  though  in  an  unequal  degree.     Yet  every 
animal,  the  highest  and  the  lowest,  the  man  and  the  worm, 
and  all  intermediate  grades  of  creatures,  must  sustain  life 
by  their  breath.     All  of  these,   from  the  first  to  the  last  mo- 
ment of  their  existence,  are  continually  absorbing  and  con- 
suming the  life-giving  oxygen  of  the  air,  and  sending  back 
in  its  stead  the  poisonous  carbonic  acid  gas. 

394.  The  air  covers  the  whole  globe,  and  reaches  to  forty- 
five  or  fifty  miles  from  it.     It  is  so  subtile,  that  it  penetrates 
the  smallest  crevice ;  and,  if  not  excluded  by  other  matter,  it 
fills  all  space  within  forty-five  or  fifty  miles  of  the   earth. 
Yet,  abundant  as  this  air  is,  it  might  be  feared  that  the  respi- 
ration of  so  many  millions  of  creatures,  carried  on  for  thou- 
sands of  years  since  the  world  began,  would  consume  all  its 
oxygen,  and  leave  nothing  but  nitrogen,  and  carbonic  acid 
gas,  and  vapor,  in  its  place. 

395.  To  one  who  looks  no  farther  into  the  order  of  na- 
ture, this,  perhaps,   might  be  a  reasonable     fear.      But    a 

*  Carpenter's  Physiology,  p.  393. 

15 


170  PHYSIOLOGY   AND   HEALTH. 

more  thorough  examination  of  the"  plans  of  the  benevolent 
Author  of  all  things,  shows  that  there  is  no  natural  want 
without  a  due  supply.  And  if  that  want  be  permanent,  the 
means  of  gratifying  it  are  equally  so,  and  coextensive  w  ith  it. 
The  works  of  the  Creator  are  all  arranged  in  infinite  wisdom. 
There  is  no  deficiency  —  there  is  no  want  of  harmony. 
The  oxygen,  which  is  so  continually  and  universally  con- 
sumed by  the  animal  creation,  is  restored  by  agents  equally 
universal  and  permanent. 

396.  Animals   and    vegetables    meet    each   other's   wants, 
and  supply  each  others  necessities.     The   animal   uses  oxy- 
gen, and  gives  out  carbonic  acid  gas ;  while,  on  the  other 
hand,  the  plant  uses  carbonic  acid  gas,  and  gives  out  oxygen. 
The  vegetables,  like  animals,  breathe  air;  but,  unlike  them, 
they  breathe  it  for  the  carbonic  acid,  and  not  for  the  oxygen. 
Through  the  leaves  of  some,  which  are  provided  with  them, 
and  through  the  bark  of  others,  the  carbonic  acid  is  absorbed 
from  the  air,  and  then,  within  this  vegetable  respiratory  ap- 
paratus, it  is  decomposed  —  the  carbon  is  retained  to  nourish 
the  plant,  while  the  oxygen  is  thrown  out  for  the  use  of  the 
animated  creation.     Thus   the  equilibrium   is   maintained ; 
and,  as  long  as  both  live  together,  there  need  be  no  fear  of 
their  suffering  for  want  of  air  suited  to  their  necessities. 

397.  This  process  of  respiration    of   vegetables  is    con- 
ducted only  in   the  presence  of  light.     In  its   absence,  in 
darkness,  precisely  the  reverse  takes  place,  and  the  vegetable 
respiration  is  similar  to   that   of  animals  —  oxygen    is  ab- 
sorbed, and  carbonic  acid  given  out. 

398.  Plants,    then,  as  they  aid  animal  respiration  when 
they  have  the  light  of  the  sun,  are  proper  and  healthy  accom- 
paniments of  any  inhabited  room  in  the  daytime.     But,  on 
the  other  hand,  as,  in  darkness,  they  consume   the  oxygen 
that  animal  respiration  needs,  they  are  unhealthy  and  inju- 
rious to  be  kept  in  rooms  which  are  occupied  in  the  night 
for  sleeping  or  other  purposes. 


ANIMAL    HEAT.  171 

PART    IV. 

ANIMAL  HEAT. 


CHAPTER  I. 

Internal  Heat  of  living  Bodies  usually  greater  than  the  Heat  of  sur- 
rounding dead  Matter.  —  Whales  and  Porpoises  in  the  Arctic 
Ocean  as  warm  as  at  the  Equator.  —  Man's  Heat  does  not  vary 
in  Extremes  of  Temperature.  —  Blagden's  Experiment.  —  Natural 
Tendency  to  Equilibrium  of  Heat  in  all  dead  Matter.  —  Living 
Matter  sustains  its  own  Heat. 

399.  IT  is  easy  to  see  that  the  temperature  of  most  ani- 
mals is  higher  than  the   surrounding   medium.     Our   own 
bodies  are  usually  warmer  than  the  air  about  us.     In  winter, 
especially,  when  water  freezes  and  the  air  is  colder  than  ice, 
this  fact  is  to  be  noticed.     If  we  then  lay  our  hands  upon 
the  body  of  a  horse  or  a  kitten,  or  upon  our  own  flesh,  we 
find  them  to  be  warmer  than  the  air.     If  we  take  ice  into 
our  hands,  it*  melts,  from  the  natural  heat  of  our  flesh ;  and 
yet  this  flesh  is  not  cooled  down  to  the  coldness  of  ice,  and, 
although  it  loses  a  little  heat  while  it  is  in  contact  with  the 
ice,  it  soon  recovers  it  after  the  ice  is  taken  away. 

400.  The  porpoise  and  the  whale  dwell  under  the  ice,  in 
the  waters  of  the  Northern  Ocean.     Above  them,  the  air  may 
be  cooled  down  to  50°  below  freezing  point ;  the  temperature 
of  the  ice  is  at  least  as  low  as  32°,  and  the  water  is  nearly 
as  cold,  and  yet  they  are  warm.     Their  temperature  is  sus- 
tained at  about  100°,  as  high  as  that  of  other  animals  of  the 
same  kind,  in  the  burning  regions  of  the  equator. 

401.  Man  dwells  in  all  climates;   he   finds   a   home  in 


172  PHYSIOLOGY   AND   HEALTH. 

every  country,  from  the  equator  almost  to  the  poles.  Under 
the  equator,  the  temperature  of  the  atmosphere  is  elevated  to 
100°,  bodies  exposed  to  the  sun  are  heated  to  130°,  and  the 
inhabitants  are  there  subjected  to  a  perpetual  heat.  In  the 
northern  regions,  Captain  Parry  found  the  thermometer  as 
low  as  55°  below  zero;  and  Captain  Back  found  it  15°  lower 
than  this,  or  70°  below  zero.  These  were  87°  and  102°  below 
freezing  point.  And  yet,  in  these  extremes  of  external  tem- 
perature, the  internal  heat  of  the  human  body  varies  very 
little.  There  are  greater  differences  than  even  this.  In 
France,  some  bakers  entered  their  ovens  heated  up  to  278°, 
or  66°  warmer  than  boiling  water,  without  increasing  their 
own  heat.  And  some  philosophers  of  London  tried  the  ex- 
periment, to  ascertain  how  great  heat  could  be  borne  without 
injuring  or  increasing  the  temperature  of  the  living  body. 

402.  Sir  Charles  Blagden  entered  a  room,  prepared  for 
the  purpose,  in  which  the  thermometer  stood  at  260° ;  and 
there  he  staid  for  eight  minutes.     Eggs  were  put  into  the 
same  room,  and  were  soon  roasted  quite  hard.     "  Beefsteak 
was  not  only  dressed,  -but  almost  dry."     And  yet  here,  in 
this  great  heat,  in  which  water  boiled  and  meat  was  cooked, 
the  thermometer,  when  placed  under  the  tongue,  was  raised 
only  to  100°,  two  degrees  above  the  usual  standard.     There 
have  been  many  other  experiments  and  observations  of  this 
kind,  which  show  the  same  principle — that  the  heat  of  the 
living  body  does  not  change,  or  changes  very  slightly,  with 
the  temperature  of  the  air  or  water  which  surrounds  it.     A 
dyer  will  hold  his  hands  in  water  at  the  temperature  of  130°, 
and  the  ice-cutter  has  his  hands  in  contact  with  ice  at  32° ; 
and,  in  both  instances,  the  temperature  of  the  body  is  about 
the  same,  neither  raised  in  one  case,  nor  depressed  in  the 
other,  materially. 

403.  There  is  a  natural  and  almost  universal  tendency  to 
equilibrium  of  heat.    When  a  warm  and  a  cold  dead  body  are 
brought  in  contact,  their  heat  is  shared  in  common  between 
them.     One  loses,  and  the  other  gains,  heat,  so  that  in  a 


ANIMAL    HEAT.  173 

short   period,   they   have    equal    temperatures;    neither   is 
warmer  or  colder  than  the  other. 

404.  If  a  piece  of  wood  or  of  dead  flesh  be  put  into  hot,  or 
even  boiling  water,  it  soon  is  as  warm  as  the  fluid.     If  it  be 
put  into  cold  water  or  snow,  it  soon  becomes  as  cold  as  that. 
If  ice  be  put  into  hot  water,  it  receives  a  part  of  the  heat  of 
the  fluid.     It  first  melts,  and  its  water  is  then  warmed  up  to 
the  temperature  of  the  original  water ;  while  this,  losing  its 
heat,  is  cooled  down  to  the  temperature  of  the  water  from 
the  ice,  and,  finally,  both  have   the   same   degree  of  heat. 
The  same  effect  is  seen  when  any  substances  are  placed  in 
air  of  different  temperature.     When  the  atmosphere  is  at  32°, 
water  freezes,  and  solids  become  as  cold  as  ice.     On  the 
other  hand,  water  boiled,  and  the  eggs  and  the  beef  were 
heated  up  to  the  temperature  of  the  room  \fhich  Sir  Charles 
Blagden  entered. 

405.  But  it  is  not  so  with  living  beings.     Their  tempera- 
ture does  not  follow  that  of  the  surrounding  and  contiguous 
objects.     The  temperature  of  the  warm-blooded  animals, — 
of  man,  horses,  and  birds,    for   instance,  —  scarcely   varies 
with  any  extremes  of  cold  or  heat  to  which  they  may  be  ex- 
posed.    The  usual  temperature  of  man  is  98°.     If  a  ther- 
mometer be  placed  in  his  mouth,  in  the  East  Indies  or  in 
the  arctic  regions,  it  will  be  found  the  same.     The  body 
sustains  its  own  temperature  in  the  cold  medium,  and  is  no 
warmer  in  the  heated  room. 

406.  If  this  were  not  so,  if  the  temperature  of  our  bodies 
should  follow  that  of  the  surrounding  medium,  the  most  fatal 
consequences  would  ensue.     The  blood  and  the  flesh  would 
be  frozen,  and  all  our  motions  stayed,  and  life  extinguished, 
in  the  severe  weather  of  winter,  even  in  the  temperate  cli- 
mates; and,  on  the  other  hand,  the  fatty  portions  of  our 
frame  would  sometimes,  in  the  tropical  climates,  melt,  and 
the  blood  would  boil  in  such  experiments  as  Blagden  tried. 

15* 


174  PHYSIOLOGY   AND   HEALTH. 


CHAPTER  II. 

Law  of  Equilibrium  of  Heat  different  in  Regard  to  living  and  dead 
Matter.  —  Animals  maintain  their  own  Temperature,  and  give 
Heat  to  other  Bodies.  —  Animal  Heat  generated  within. —  Warm 
and  cold  blooded  Animals.  —  Power  of  sustaining  Heat  varies 
with  respiratory  Apparatus.  —  Fishes  breathe  by  Gills,  and  have 
little  Heat.  —  Whales  breathe  by  Lungs,  and  have  much  Heat.  — 
Animals  have  internal  Apparatus  for  generating  Heat. 

407.  BESIDE  this  maintenance  of  its  own  warmth,   the 
living  animal  body  is  continually  giving  out  heat  to  other 
substances  which  are  cooler  than  itself;  and  yet  it  does  not 
apparently  lose  its  own  heat ;  at  least  its  temperature  remains 
undiminished.     If  we  hold  a  piece  of  ice  in  our  hand,  it  is 
melted,  but  the  hand  is  not  much  cooled ;  or,  if  cooled,  it 
soon  regains  its  heat  after  being  separated  from  the  ice.     But, 
if  we  place  the  ice  upon  a  piece  of  iron  heated  to  the  tem- 
perature of  the  hand,  the  ice  melts  there,  as  in  the  other 
case,  and  the  iron  is  cooled  down  to  a  lower  temperature,  and 
the  waiter  of  the  ice  is  raised  to  the  same  degree.     The  ice 
cools  the  iron,  and  the  iron  warms  the  water  of  the  ice ;  and 
then  the  temperature  of  both  remains  the  same,  until  some 
external  influence  changes  it. 

408.  Here,  then,  is  a  manifest  difference  in  the  law  that 
governs  the  heat  of  living  and  that  of  dead  substances.     One 
class  seems  to  have  heat  only  in  common  with  contiguous 
and  surrounding  objects.     If  they  are  warm,  the  dead  matter 
becomes  warm ;  if  they  are  cold,  this  is  cooled  to  the  same 
degree.     It  neither  warms  itself  nor  cools  itself,  but  depends 
upon   others   for   its   heat.     But  the  living  body  is  neither 
cooled  nor  heated   materially  by  surrounding   matters.     Its 
own  heat  seems  to  be  independent  of  them. 

409.  Our  heat  is  not  borrowed  from  external   objects; 
certainly  not  from  the  atmosphere,  for  we    have  seen  that 
the  human  bodies  are  warm  when  the  air  is  extremely  cold ; 
nor  from  the  sun  or  fire,  for  we  are  warm  in  the  absence  of 


ANIMAL,  HEAT.  175 

both.  Nor  is  our  heat  derived  from  clothing,  foi  this  has  no 
active  power  of  giving  heat  —  it  has  no  warmth  in  itself;  it 
only  tends  to  prevent  changes  of  temperature.  If  we  wrap  a 
piece  of  dead  flesh  in  flannel,  it  is  not  warmed ;  it  remains 
the  same  as  before.  If,  in  the  winter,  this  flesh  be  heated 
by  fire,  the  flannel  wrapped  about  it  keeps  it  warm.  If,  in 
summer,  we  put  ice  in  flannel,  it  prevents  the  melting. 
Clothing,  then,  only  prevents  the  passage  of  heat.  It  keeps 
a  warm  body  warm,  and  a  cool  body  cool;  but  it  creates 
and  gives  no  heat.  If,  then,  animal  heat  is  not  given  from 
without,  it  must  originate  within  the  body.  There  must  be 
some  internal  means  or  apparatus  by  which  we  and  other 
living  beings  create  and  sustain  our  temperature. 

410.  There  are  two  grand  classes  of  animals,  divided  ac- 
cording  to   their   temperature.      One   is  called   the  warm- 
blooded, and  includes  man,  birds,  quadrupeds,  &-c.     Their 
heat  is  ever  of  the  same  degree,  and  does  not  vary  with  the 
temperature  of  the  atmosphere  or  the  water  in  which  they 
live.     The  other  class  is  called   cold-blooded,  and  includes 
snakes,  oysters,  fishes,  worms,  toads,  turtles,  &/c.     Their  heat 
is  but  little  higher  than  that  of  the  medium  in  which  they  live. 
The  earth-worm,  leech,  and  shell-fish  are  usually  1J°  warmer 
than  the    air,   or   earth,   or  water    which    surrounds   them. 
Fishes  are  2°  to  5°  warmer  than  the  water.     Reptiles,  frogs, 
lizards,  have  a  still  higher  heat  relative  to  the  air  or  water, 
yet  not  so  high  and  permanent  as  that  of  the  warm-blooded 
animals. 

411.  There  is,  in  these  two  great  classes,  a  great  differ- 
ence of  power  of  maintaining  their  own  heat.     Man  main- 
tains his  usual  temperature  in  the  midst  of  air  varying  320° 
from  extreme  heat  to  extreme  cold ;  and  therefore  he  may  be 
at  least  160°  warmer,  or  160°  cooler,  than  the  surrounding 
medium ;  while  a  fish  is  only  2°  or  3°  warmer  or  cooler  than 
the  water  in  which  it  lives.     It  is  natural,  then,    to    ask, 
What  is  the  difference  in  the  structure  of  these  classes,  from 
which  arises  this  difference  of  internal  heat  1     On  examina- 
tion, we  find  that  the  principal  difference  that  runs  through 


1'6  PHYSIOLOGT 'AND    HEALTH. 

the  whole  of  these  classes  is  in  the  apparatus  of  respiration. 
The  warm-blooded  animals  breathe  more  and  purer  air  than 
the  cold-blooded.  Fishes  breathe  only  .by  gills,  and  receive 
only  the  little  air  that  is  in  the  water,  and  they  are  cold ; 
we  breathe  with  full  lungs,  and  receive  a  more  plentiful  sup- 
ply of  air,  and  are  heated  to  98°  ;  while  birds  have  the  largest 
means  of  respiration,  and  breathe  the  purest  air,  and  are 
consequently  from  2°  to  13°  warmer  than  even  man.  Insects 
have  generally  larger  means  of  respiration,  and  a  higher 
temperature. 

412.  There  is  a  remarkable  difference,  in  this  respect, 
among  the  inhabitants  of  the  sea.     Fishes  —  such  as  the  pike, 
cod,  haddock,  sturgeon,  smelt,  &c.  —  which  breathe  by  gills 
are  dependent  solely  upon  the  air  in  the  water.     They  can 
therefore  neither  obtain  nor  consume  more  than  a  very  small 
portion  of  air,  and  consequently  they  are  cold.     On  the  con- 
trary, whales,    porpoises,    and    dolphins    breathe    by    lungs. 
They  rise  to  the  surface  of  the  water,  and  inhale  the  free  air 
above  it.     They  find  this  abundant,  and  consume  it  plenti- 
fully, and  consequently  their  temperature  is  about  100°,  and 
independent  of  the  heat  of  the  water.     It  is  neither  depressed 
in  winter  nor  raised  in  summer.     They  are  therefore  classed 
with  the  warm-blooded  animals. 

413.  In  order  to  maintain  this  heat  within  the   animal 
body,  constantly  and  independently  of  the  influence  of  sur- 
rounding and  contiguous  matters,  two  conditions  are  neces- 
sary :   1st,  each  animal  must  possess  some  internal  appara- 
tus for  generating  or  creating  this  heat ;  2d,  the  skin,  or  the 
external  covering,  must  be  endowed  with  such  a  power  of 
regulating  the  transmission  of  heat,  that  it  may  prevent  its 
too  rapid  passage  out  in  winter,  or  when  the  air  is  colder 
than  the  body,  and  also  its  passage  into  the  body  in  summer, 
or  when  the  air  is  warmer  than  the  body. 


ANIMA 


CHAPTER    III. 

Latent  and  sensible  Heat.  —  Heat  applied  to  Ice  forms  Water,  and 
to  Water,  makes  Steam. 

414.  THE  warm-blooded  animals  breathe  more  than  the 
cold-blooded,     The  same  difference  prevails  among  the  sub- 
divisions of  these  classes,  for  the  warmest  kinds  breathe  more 
than  the  coldest.     It  would  seem,  then,  that  the  internal  heat 
arises  out  of,  or  is  in  some  way  connected  with,  respiration. 
And  this  we  find  to  be  strictly  true,  upon  examination  of  the 
nature  and  properties  of  the  elements  of  air,   and  of  the 
chemical  effects  produced  by  this  gas  upon  the  blood  and 
particles  of  the  animal  body. 

415.  When  ice  is  melted  and  changed  to  water,  it  is  easy 
to  see  that  heat  is  given  to  it,  and  absorbed  by  it.     The  heat 
necessary  to  produce  this  change  has  united  with  the  ice, 
and  both  together  have  become  water.     Again,  if  much  more 
heat  is  applied  to  this  water,  it  boils  and  is  changed  to  vapor 
or  steam.     By  continuance  of  the  same  process  that  pro- 
duced the  first  change,  the  second  one  is  produced ;  and,  by 
the  union  of  heat  with  water,  steam  is  formed.     It  is  obvious 
that  steam  contains  more  heat  than  water,  and  water  more 
heat  than  ice.     Heat  added  to  ice  produces  water,  and  heat 
added  to  water  produces  steam  ;  and,  in  both  cases,  most  of 
the  heat  becomes  latent  or  hidden  in  the  new  substance. 
If,  now,  we  reverse  the  process,  and  return  the  steam  back 
to  water,  heat  must  be  given  out.     Just  so  much  is  given  out 
as  was  originally  required  to  convert  the  water  into  steam. 
If  we  continue  this  process  further,  and  change  the  water  to 
ice,  there  must  be  a  further  discharge  of  heat;  and  as  much 
heat  will  be  given  out,  in  this  process  of  freezing  the  water, 
as  was  before  required  to  melt  the  ice. 

416.  There  is  a  general  law  of  matter,  that  rare  or  light 
substances  require  more  heat  than  dense  or  heavy  matters. 
Liquids  commonly  require  more  heat  than  solids,  and  gases 
more  than  liquids,  to  keep  them  in  their  respective  states; 


178  PHYSIOLOGY    AND    HEALTH. 

and  abstracting  heat  renders  them  more  solid,  while  adding 
heat  renders  them  more  fluid.  By  a  great  reduction  of  tem- 
perature, airs  or  gases  can  be  condensed  to  fluids ;  and, 
during  this  change,  heat  is  given  out. 

417.  The  apparent  heat  of  a  body,  as  measured  by  the 
thermometer,  or  as  perceived  by  the  touch,  is  not  always  an 
exact  measurement  of  the  quantity  of  heat  in  that  body.     If, 
for  instance,  we  mix  a  pound  of  water  heated  to  100°,  with 
a  pound  of  spermaceti  oil  at  50°,  it  might  be  supposed  that 
the  temperature  of  the  mixture  would  be  75°,  the  exact  me- 
dium between  them.     This  would  be  the  case,  if  each  of 
these  bodies  were  raised  to  the  same  temperature  by  the 
same  quantity  of  heat.     But  the  temperature  of  the  mixture 
is  actually  83J°.     If,  again,  the  experiment  be  reversed,  and 
water  at  50°,  and  oil  at  100°,  be  mixed,  the  result  is  a  tem- 
perature of  66§°.     Instead  of  the  warmest  substance  losing 
25°,  and  the  coolest  gaining  as  much  heat,  we  find  that,  in 
the  first  instance,  the  water  loses  only  16|°,  while  the  oil 
gains  33J° ;  and,  in  the  other  case,  the  oil  loses  33J°,  and 
the  water  gains  16|°.     That  is,  the  quantity  of  heat  that  will 
warm  water  16  J°  will  warm  oil  33  J° ;  or,  the  water  requires 
twice  as  much  heat  as  oil  does,  to  raise  it  to  any  definite 
temperature.     It  will,  then,  be  clearly  understood,  that  the 
same  substance  has  different  quantities  of  heat  in  its  different 
states ;  and  also  that  one  substance  requires  more  heat  than 
another  to  give  it  the  same  apparent  heat. 

418.  The   burning   of  wood    and    all  other    fuel    shows 
both  of  these  principles.     Oxygen  exists  in  the  air  in  the 
state  of  gas.  (§  292,  p.  133.)     When  wood  or  coal  is  heated, 
this  oxygen  combines  with  the  carbon  of  the  fuel,  and  forms 
carbonic  acid.     In  this  process,  the  oxygen  enters  into  a 
new  state,  and  becomes  a  part  of  a  compound  more  dense 
than    it  was  before.      Oh  two  accounts  it  loses  heat ;  1st, 
oxygen    has  greater  capacity  for,  or  holds  more,  heat  than 
carbonic    acid  gas,    and  therefore,   when   this   new   gas   is 
formed,  the  surplus  heat,  or  that  excess  of  heat  which  oxygen 
can  hold  over  that  which  the  other  gas  can  hold,  must  be 
given  out ;    2d,  the  oxygen   is    in    a  denser  state   when  it 


ANIMAL    HEAT.  179 

composes  a  part  of  the  carbonic  acid  gas  than  when  it  is 
pure  and  uncombined,  and  therefore  holds  less  heat,  (§  416,  p. 
177,)  and  must  give  out  some  when  it  enters  the  compound. 
From  both  of  these  causes,  heat  is  derived  from  fire  of  every 
kind.  Whatever  may  be  the  theory  or  explanation,  the  fact 
is  evident,  that  heat  is  evolved  from  the  union  of  oxygen 
with  fuel  —  carbon  or  hydrogen.  This  is  what  we  call  com- 
bustion or  jire*  The.  amount  of  heat  thrown  out  from  this 
union  or  combustion  is  always  in  proportion  to  the  amount 
of  material  consumed.  A  pound  of  wood  in  a  solid  block 
gives  out  the  same  quantity  of  heat,  in  burning  slowly,  as  a 
pound  of  shavings  of  the  same  wood,  in  burning  rapidly. 

419.  Upon  these  principles,  it  will  now  be  easy  to  under- 
stand how  the  warmth  of  the  animal  body  is  obtained.     The 
particles  of  our  flesh  are  continually  changing.  (§§  242 — 244, 
pp.  Ill,  112.)     The  old  ones  are  going  away,  and  new  ones 
taking  their  places.     The  principal  components  of  these  old 
particles  are  carbon,  nitrogen,  and  hydrogen.  (§  290,  p.  132.) 
When  the  air  is  received  into  the  lungs,  and  brought  into 
contact  with  the  old  and  venous  blood,  it  is  decomposed,  or 
divided  into   its  two  elements ;  the  oxygen  is  separated  from 
the   nitrogen,  and    united  with  the    blood.  (§  297,  p.  135.) 
The  blood,  at  the  same  time,  throws  out  into  the  air  carbonic 
acid  gas  and  vapor,  (§§297,  303,  pp.  135,  137;)  and  then, 
being  relieved  of  these  impurities,  it  is  returned  to  the  heart, 
and  thence  it  is  circulated  throughout  the   body,   carrying 
the  newly-acquired  oxygen  with  it. 

420.  It  was  once  generally  believed,  by  chemical  physi- 
ologists, that   the  oxygen  does  not  enter  the  blood,  but 
that  these  dead  particles  are  brought  unchanged  to  the 
lungs,  and  there  the  carbon  and  the  hydrogen,  meeting  the 
oxygen,  combine  with  it,  and  form   carbonic   acid  gas  and 
water,  which  are  given  out  with  the  returning  air. 

421.  But  it  is  now,  with  better  reason,  supposed,  that 
the  oxygen  of  the  air  enters  the  minute  arteries  in  the  lungs, 
and  is  there  mingled  with  the  blood.     It   is  then    carried 
with  this  blood  to  the  heart,  and  thence  sent  through  the  ar- 
teries all  over  the  body.     When  this  blood,  and  the  oxygen 


180 


PHYSIOLOGY    AND    HEALTH. 


which  it  carries  along  with  it,  reach  the  minute  arteries  and 
the  capillaries,  where  the  work  of  nutrition  is  carried  on, 
the  interchange  of  the  old  for  the  new  particles  of  flesh  takes 
place.  The  old  —  those  which  have  finished  their  work  and 
are  dead  —  give  way,  and  the  new  ones,  fresh  with  living 
vigor,  take  their  stations  and  perform  their  part  in  the  work 
of  life.  As  these  old  and  dead  atoms  of  flesh  pass  from  their 
stations  to  the  vessels,  the  oxygen  in  the  blood  meets  them, 
and  they  unite  together  and  form  new  compounds.  The 
union  of  the  oxygen  with  the  carbon  produces  carbonic  acid, 
and  its  union  with  hydrogen  produces  water.  These  unions 
take  place  in  the  same  manner,  and  the  same  results  follow, 
as  when  the  carbon  of  the  wood  in  the  fireplace,  and  the 
hydrogen  of  the  gas  lamp,  unite  with  oxygen.  The  carbon 
and  the  hydrogen  are  burned,  fire  is  produced,  and  heat  is 
evolved ;  the  carbonic  acid  and  the  water  are  then  carried 
through  the  veins  to  the  heart  and  the  lungs,  and  the  heat  is 
left  in  the  textures  of  the  living  body.  During  this  process, 
precisely  the  same  amount  of  heat  is  given  out  from  this  in- 
ternal fire  —  this  slow  combustion  of  the  wasted  particles  of 
flesh — as  would  result  from  the  combustion  of  the  same 
amount  of  fuel,  carbon,  and  hydrogen  elsewhere. 


CHAPTER   IV. 

Exercise  increases  Combustion  of  Carbon  and  Evolution  of  Heat. — 
Whatever  increases  Flow  of  Blood  increases  Heat,  and  whatever 
diminishes  Flow  of  Blood  lessens  Heat.  —  Oxygen  and  Fuel  neces- 
sary to  support  internal  Fire.  —  Whatever  interrupts  Supply  of 
Oxygen  or  Air  to  Lungs,  prevents  Development  of  Heat.  —  Tight- 
Lacing  lessens  Heat.  —  Bad  Air — foul  Air  —  lessen  it.  —  Food 
supplies  Fuel.  —  Well-fed  warmer  than  the  Ill-fed.  —  Alcohol  does 
not  increase  the  Heat  of  the  Body.  —  Meat  supplies  more  Fue 
than  Bread.  —  More  Meat  eaten  in  cold  than  in  warm  Weather. 

422.    THIS  work  of  interchange  of  particles,  and  of  burn- 
ing the  old  flesh,  is  carried  on  throughout  the  whole  body ; 


ANIMAL    HEAT.  181 

consequently,  every  part  of  the  body  is  warmed.  The  more 
rapid  is  the  circulation  and  the  more  frequent  are  the 
changes  of  living  for  dead  particles,  the  more  carbon  and 
hydrogen  are  burnt,  and  the  greater  is  the  heat  given  out. 
Whatever  increases  the  interchange  of  particles,  the  work  of 
absorption  and  nutrition,  and  consequently  the  flow  of  blood, 
increases  the  internal  fire  and  the  evolution  of  heat.  Motion 
is  attended  with  greater  waste  of  particles,  and,  of  course, 
with  greater  absorption  of  carbon  and  hydrogen,  (§  127,  p. 
61,)  and  greater  development  of  heat.  Labor,  therefore, 
warms  the  body,  and,  if  violent,  may  heat  it  uncomfortably. 
The  watchman  keeps  himself  warm  with  exercise,  and  the 
passenger  leaves  the  vehicle  to  warm  his  feet  with  running. 
The  hardy  laborer  heats  himself  with  his  exercise,  and  sits 
down  quietly  to  cool  his  body.  ^ 

423.  On  the  contrary,  whatever  interrupts  the  circulation 
and  the  interchange  of  particles  prevents  the  development  of 
heat.     If  we  bind  up  the  arm  or  finger  with  a  tight  cord, 
and  prevent  the  flow  of  the  blood  through  it,  the  limb  be- 
comes cold.     It  is  a  common  and  a  true  observation,  among 
shoemakers,  that  a  loose   boot  is  warmer  in  winter  than  a 
tight  one,  because  the  latter  presses  upon  the  blood-vessels, 
and  interrupts  the  full  flow  of  blood.     So  we  find,   if  one 
side  or  one  limb  be  palsied,  that  side  or  that  limb  becomes 
cold,  for  the  same  reason. 

424.  This  animal  heat  then,  is  sustained  by  the  combus- 
tion of  the  dead  atoms  of  the  flesh  in  all  the  parts  of  our 
frames  where  the  blood  circulates.     In  order  to  maintain 
this   combustion,    the   same   things    are   requisite   that    are 
needed  to  support  fire  elsewhere ;  these  are  fuel  and   air. 
To  deprive  the  body  of  either  would  be  as  fatal  to  its  internal 
heat  as  taking  away  the  fuel  or  the  air  would  be  to  the  fire 
of  the  stove.     As  the  wood  in  the  fireplace  burns  by  aid  of 
the  oxygen  which  it  derives  from  the  air,  and  as  this  fire 
burns  freely  in  proportion  to  the  quantity  of  air  which  it 
receives,  so  the  internal  fire  of  the  animal  body,  deriving  its 
oxygen  from  the  air,  burns  in  proportion  to  the  fulness  of  its 

16 


182  PHYSIOLOGY    AND    HEALTH. 

supply.  Consequently^whatever  impedes  the  flow  of  air  into 
the  lungs,  and  its  access  to  the  blood,  must  so  far  prevent 
the  development  of  internal  heat,  as  certainly  as  any  inter- 
ruption of  the  draught  or  diminution  of  air  would  lessen  the 
fire  and  the  heat  of  the  fireplace. 

425.  Whatever,  then,  restricts  the  expansion  of  the  chest, 
or  limits  the  capacity  of  the  lungs  for  the  admission  of  air, — 
any  pressure  of  clothing  without  that  prevents  the  motions 
of  the  ribs  or  the  diaphragm,  or  any  disease  of  the  lungs  that 
closes  the  air-cells  within,  —  any  of  these  obstructions,  by 
lessening  the    amount  of  oxygen  that   the   blood    receives, 
diminishes  the  combustion  of  the  atoms  of  dead  flesh  and 
the  evolution  of  the  internal  heat,  as  certainly  as  shutting 
the  draught  of  a  stove  would  lower  or  extinguish  its  fire.     For 
this  reason,  asthmatic  persons,  and  those  whose  air-cells  are 
partially  closed  with  disease,  are  only  partially  warmed,  and 
cannot  endure  so  severe  a  cold  as  men  in  health.     A  poor 
woman,  whom  I  saw  sick  with  consumption  in  a  very  cold 
room,  was  frozen   to  death,  one  night,  in  her  bed,  in  the 
winter  of  1830,  while  some  other  women,  who  slept  in  the 
same  room,  and  under  the  same  quantity  of  clothing,  awoke 
in  vigor,  though  suffering  with  cold. 

426.  Nothing  but  oxygen  can  support  this  internal  com- 
bustion of  fuel.     We  must  not  only  receive  a  sufficiency  of 
air  into  the  lungs,  but  that  air  must  contain  its  due  propor- 
tion of  this  gas.     If,  then,  the  air  contains  less  than  the  due 
quantity,'  if  it  has  been  breathed  over,  and  its  oxygen  has 
been  consumed,  or  if,  in"  consequence  of  mixture  with  other 
gases,  the  twenty  inches  which  we  inhale  conta  n  less  than 
twenty  per  cent.  of*>xygen,  then  the  internal  combustion  is 
impeded,  heat  is  sparingly  evolved,  and  those  who  breathe 
this  impure  or  weakened  air  are  comparatively  cool.     After 
a  crowd  has  been  long  in  session  in  a  close  hall,  or  children 
in    an    unventilated  school-room,  in  winter,  they   begin    to 
complain  of  being  cold.     Notwithstanding  the  fire  may  glow 
in  the  stove,  and  the  thermometer  indicate  no  reduction  of 
temperature,  still,  for  want  of  oxygen  in  the  vitiated  air,  the 


ANIMAL    HEAT.  183 

fire  burns  languidly  in  the  bodies  of  the  people,  they  are 
not  well  warmed,  and  their  sensations  persuade  them  that 
the  room  is  growing  cooler. 

427.  The   narrow-chested    are    colder    than   the   broad- 
chested  ;  the  tight-bound,  than  the  loosely-dressed  ;  and  those 
who  breathe  the  impure  air  of  close  arid  unventilated  rooms, 
than  those  who  breathe  the  free  air  of  the  fields.     The  former 
need  more  external  protection  of  houses  or  clothing,  or  more 
outward  heat  from  fires,  than  the  others.     A  free  expansion 
of  the  chest,  with  a  good  supply  of  pure  air,  is,  therefore,  an 
economy  of  clothing  and  of  fuel.     When  the  air  is  dense 
and  heavy,  as  when  cooled,  it  contains  a  greater  weight  of 
oxygen  to  the  cubic  inch,  than  when  it  is  rare  and  light,  as 
when  heated.     We  therefore  breathe  more  oxygen  in  winter 
than  in  summer,  and  the  fire,  consequently,  burns  most  ac- 
tively when  it  is  the  most  needed. 

428.  Fuel,  as  well  as  air,  is  necessary  to  keep  up  this 
internal  combustion  in  the  animal  body.     This  is  supplied  by 
the  atoms  of  wasted  flesh  that  have  died  in  the  various  tex- 
tures, and  are  ready  to  be  burned  or  combine  with  oxygen,  and 
need  to  be  carried  away.     The  combustible  matters  of  the 
flesh  —  its  carbon  and  hydrogen  —  are  originally  supplied  by 
the  food  that  contains  the  same  materials.      These  elements 
of  the  food,  being  converted  first  into  chyle,  then  into  blood, 
arid  next   into  flesh,  are  at  last  burnt  by  their  union  with 
oxygen,  and  carried  out  through  the  veins  and  the  lungs. 
As  the  food  is  the  only  source  from  which  this  fuel  is  sup- 
plied, of  course,  all   other  things   being  equal,  the  internal 
fire  must  burn,  and  the  body  be  warmed,  in  proportion  to  the 
amount  of  carbon  and  hydrogen  which  is  eaten,  and  incor- 
porated into  and  becomes  a  part  of  the  tissues. 

429.  The  well-fed  and  well-nourished,  —  those  who  live 
upon  good  and  generous  food,  —  having  a  better  supply  of 
fuel,  are  therefore  better  warmed  than  the  hungry,  or  those 
who  live  upon  a  poor  and  meagre  diet.     The  traveller  who 
has  been  long  exposed  to  the  severe  weather  without  eating, 
in  winter,  complains  that  he  is  both  hungry  and  cold.     His 


184  PHYSIOLOGY    AJSD    HEALTH. 

hunger  and  his  low  temperature  may  seem  to  him  to  be  mere- 
ly coincident  circumstances,  accidentally  coming  together; 
but,  in  truth,  one  is  the  cause  of  the  other.  For  want  of 
food,  his  body  is  not  supplied  with  fuel,  and  its  internal  fire 
burns  feebly,  arid  therefore  does  not  warm  him.  One  of  the 
best  means  of  protection  against  the  effects  of  exposure  to 
the  cold  air  of  winter  is  proper  nutriment. 

430.  Alcoholic  spirit  is  sometimes  taken  for  this  purpose, 
but  with  a  mistaken  view  of  its  effects  upon  the  heat  of  the 
body.     It  stimulates  the  stomach,  excites  the  nervous  system, 
and  quickens  the  action  of  the  heart,  and  the  flow  of  the 
blood.     It  supplies  to  the  flame  carbon  and  hydrogen,  the 
most  combustible  of  materials;  but  these  soon  burn  out,  and 
their  fire  is  then  exhausted,  and  the  body  is  afterward  cooler 
than  it  otherwise  would  have  been.     Food,  alone,  can  sustain 
a  permanent  fire.     Two  travellers  met,  in  a  very  cold  day  of 
January,  1810,  at  a  tavern  in  Groton,  Massachusetts.     One 
of  them  called  for  a  mug  of  hot  flip,  and  advised  the  other  to 
do  the  same ;  for,  he  said,  "  When  I  am  going  out  in  the 
cold,  I  always  drink  hot  'spirit."     The   other  refused,  but 
said,  "  When  I  am  going  out  in  the  cold,  T  eat  a  good  din- 
ner."    The  temperate  traveller  acted  from  his  own  experi- 
ence, and  also,  without  knowing  it,  upon  the  truest  physio- 
logical principles. 

431.  Flesh,  containing  more  carbon  and  hydrogen,  sup- 
plies more  fuel  to  the  fire  than  vegetable  matter.      Meat, 
therefore,  warms  a  man  more  than  bread,  and  we  eat  it  more 
freely  in  the  winter  than  in  the  summer.     For  this  reason, 
the  coachman,  the  sailor,  and  the  teamster,  who  are  exposed 
to  the  coldest  air  abroad,  need  more  meat  than  the  mechan- 
ics, who  work  in  warm  shops,  or  those  persons  whose  life  and 
occupations  are  in  warm  houses.     In  the  northern  regions, 
where  winter  reigns  with  great  severity,  there  is  a  more  rapid 
loss  of  heat  through  the  skin,  and  of  course  a  necessity  of 
creating   more    within   the  body,   than    in    the   warmer   re- 
gions, at  and  near  the  equator.     To  keep  the  body  warm, 
there  must  be  more  fuel,  or  food  containing  more  carbon  and 
hydrogen,  in  the  cold  than  in  the  hot  climate.     Nature  sup- 


ANIMAL     HEAT.  185 

plies  this  necessity  by  the  difference  of  food,  and  of  digestion, 
of  the  inhabitants  of  these  diverse  regions.  The  principal 
diet  of  the  people  within  the  torrid  zone  is  of  vegetable  ori- 
gin, while  the  inhabitant  of  the  frigid  zone  lives  mostly 
upon  flesh ;  and  the  people  who  inhabit  the  countries  in  the 
temperate  zones,  between  these,  have  a  mixed  diet,  in  which 
the  meat  predominates  as  they  approach  the  arctic  circle, 
and  the  vegetable  predominates  towards  the  tropics. 


CHAPTER    V. 

Other  Influences  may  affect  Supply  of  Heat. —  Some  Diseases  in- 
crease, some  diminish  it.  —  Fatigue  and  Exhaustion  lessen  Evo- 
lution of  Heat.  —  Infants  and  old  Men  have  less  Heat.  —  Less 
Heat  evolved  in  Sleep.  —  Carbon  consumed  and  Heat  evolved  in  a 
Day.  —  Heat  must  be  carried  out  of  the  Body  through  the  Skin.  — 
Evaporation  of  Perspiration  carries  off  Heat.  —  Greater  Internal 
Fire  in  cold  than  in  warm  Climates.  —  Winter  and  Summer  Con- 
stitution. —  Animals  cool  more  rapidly  in  Summer  than  Winter  at 
same  Temperature. 

432.  THIS  chemical  explanation  of  the  origin  of  animal 
heat   is   shown    at   length    in    Liebig's    Animal    Chemistry. 
There  are  doubtless  other  influences  that  affect  the  develop- 
ment of  internal  heat,  beside  the  supply  of  carbon,  hydrogen, 
and  pure  air.     It  is  ascertained  by  the  later  physiological 
chemists  that  this  process  of  combustion  or  combination 
of  oxygen  with  carbon  and  hydrogen  accounts  for  only  a 
part  of  the  heat  that  is  developed  in  the  animal  body.    "  An- 
imal heat  is  a  phenomenon  which  results  from  the  simulta- 
neous activity  of  many  different  processes,  taking  place  in 
many   different   organs,    and   dependent,   undoubtedly,  on 
different  chemical  changes  in  each  one."  * 

433.  Even  when  the  body  is  well  supplied  with  both  good 
food  and  pure  air,  there  is  not  an  equal  development  of  heat 
in  all  states  of  the  system.     In  some  diseases,  such  as  fever, 

*  Dalton,  Human  Physiology,  p.  263. 
16* 


186  PHYSIOLOGY   AND    HEALTH. 

inflammations,  &c.,  the  heart  beats  quicker,  and  the  flow  of 
blood  is  more  rapid  than  natural,  and  there  is  a  greater  pro- 
duction of  heat.  But  in  some  other  diseases,  as  asthma, 
cholera,  &,c.,  there  is,  on  the  contrary,  a  greater  coldness 
The  internal  warmth  is  affected  by  the  condition  of  the 
nervous  system,  by  excitements  and  depressions,  by  the 
emotions,  the  passions,  and  the  states  of  mind.  One  is  burn- 
ing with  anger  or  with  love.  The  exciting  and  the  ardent 
passions  quicken  the  flow  of  the  blood,  and  increase  the 
internal  heat,  while  the  depressing  passions  diminish  it. 
Cheerfulness  and  merriment  promote  the  evolution  of  heat, 
while  fear,  sorrow,  and  despondency  impede  it. 

434.  Fatigue,  exhaustion,  hunger,  night-watching,  sleep- 
lessness, indigestion,  or  any  thing  that  depresses  the  system 
and  diminishes  the  energies  of  life,  lessens  the  production  of 
heat,  and  the  power  of  resisting  cold.     In  this  condition,  one 
cannot  bear  exposure  to  a  low  temperature  as  ^well  as  when 
he  is  fresh  and  vigorous.     He  is  then  more  liable  to  take 
cold.     Visiting  a  friend,  a  public  officer,  in  the  afternoon  of 
a  pleasant  day  of  March,  I  found  him  shivering  over  a  fire, 
though  otherwise  in  good  health.     He  said  that  he  had  been 
out  to  walk,  and  was  chilled.     It  was  a  warm  day,  and  other 
men   complained  of  the  heat;  but  they  were  vigorous,  for 
they  had  been  lefreshed  by  their  night's  sleep;  but  he,  hav- 
ing  an  important  report  to  finish,  had  sat  up,  and  labored 
upon  it  with  all  his  mental  energy,  until  two  o'clock  in  the 
morning;  then,  being  exhausted,  he  retired,  but  awoke  in 
the  morning  still  fatigued  and  unrefreshed ;  consequently,  he 
had  not  sufficient  power  to  maintain  his  proper  heat,  even  in 
a  temperature  which  was  comfortably  warm  to  men  in  the 
enjoyment  of  their  usual  vigor. 

435.  In  the  different  periods  of  life,  there  is  a  difference 
of  power  of  producing  internal  heat.     It  is  more  feeble  in 
infancy  and  in  old  age  than  in  the  vigorous  years  of  youth 
and  manhood.     Dr.  Edwards  exposed  some  young  and  old 
sparrows  to  a  temperature  of  64°  with  the  same  amount  of 
protection.     At  the  end  of  a  definite  period,  the  young  were 
cooled  down  to  60°,  while  the  older  birds  maintained  their 


ANIMAL    HEAT.  187 

temperature  at  102°.  Full-grown  magpies  lost  5°  of  heat  in 
the  same  atmosphere,  and  in  the  same  time  that  young  birds 
of  the  same  species  lost  25°  of  heat.  The  same  law  applies 
to  children  and  men.  Infants  and  old  men  cannot,  therefore, 
endure  the  cold  so  well  as  men  of  middle  life,  and  need  more 
careful  protection  of  clothing  when  exposed. 

436.  "  The  state  of  natural  sleep  is  in  general  accompa- 
nied by  a  diminution  of  the  power  of  producing  heat."     The 
body  is  then  more  susceptible  of  the  influence  of  cold.     Thus 
the  consumptive  woman  (§  425,  p.  182)  was  frozen  during 
her  sleep.     Night  travellers  are  in  much  more  danger   of 
suffering   from   the  cold  if  they  allow  themselves   to  sleep 
than  if  they  keep  awake. 

437.  The  amount  of  heat  given  out  from  the  combustion 
of  a  definite  quantity  of  carbon  or  hydrogen,  or  the  union 
of  either    of  these   with   oxygen,    has   been  determined  by 
experiments.     It  is  found,  also,  to  be  the  same  wherever  this 
combustion  takes  place,  whether  in  or  out  of  the  living  body, 
and  whether  it  happens  rapidly  and  with  a  flame,  as  in  the  fire 
of  a  furnace,  or  slowly,  atom  by  atom,  as  in  the  textures  of 
the   animal  body.     If,  then,   we   can  ascertain   the  amount 
of  these  elements  which  are  consumed  in  the  living  system, 
and  in  any  given  time,  we  can  determine  the  amount  of  heat 
which  will  be  then  evolved. 

438.  In  the  course  of  twenty-four  hours,  there  are,  on 
an  average,  13.9  ounces  of  carbon  converted  into  carbonic 
acid  gas,  and  given  out  from  the  lungs  of  every  adult  in 
good  health.     Every  ounce  of  carbon,  during  the  process  of 
combustion,  evolves  as  much  heat  as   would   raise   78.15 
ounces,  or  almost  five  pounds,  of  water,  at  32°,  or  the  tem- 
perature of  ice,  to  212°,  or  the  boiling  point ;  and,  conse- 
quently, the    13.9  ounces  of  carbon,  which  are  consumed 
in  the  human  body  daily,  must  give  out  heat  enough  to  raise 
67.9  pounds  of  water  from  32°  to  boiling  heat.     So  much 
heat  from  this  cause  is,  then,  generated  in  the  body  of  a 
person  of  the  average  size  and  in  good  health,  in  each  day.* 

*  Liebig's  Animal  Chemistry,  Part  I.  §  V. 


188  PHYSIOLOGY   AND    HEALTH. 

The  amount  of  hydrogen  consumed  is  not  so  easily  deter- 
mined ;  but  it  is  supposed  by  learned  chemists  that  a  great 
proportion  of  the  animal  heat  is  given  out  by  it. 

439.  If  so  much  heat  be  daily  added  to  the  body,  the 
same  amount  must  be  carried  off  in  some  way,  otherwise  it 
will  warm  the  body  too  much,  and  cause  distress.     But  it 
does  not  increase ;  when  the  body  is  at  its  usual  temperature, 
it  does  not  become  any  warmer,  although  so  much  heat  is 
continually  added  to  it.     This  quantity  must,  then,  find  its 
way   out,  through  the   surface   and   through  the   passages. 
Whatever   goes    from   the    body,  carries  some  of  its    heat. 
However  cold  may  be  the  air  which  we  inhale,  it  becomes 
warm  within  the  lungs,  and  is  then  exhaled  at  the  tempera- 
ture of  the  body. 

440.  The  skin  is  the  main  avenue  of  the  heat  outward ; 
and  through  this  it  is  continually  passing  away,  both  winter 
and  summer.     When  the  air  is  considerably  colder  than  the 
body,  it  is  very  plain  to  every  one  that  heat  goes  off  by 
transpiration  through  the  outward  surface,  in  order  to  main- 
tain an  equilibrium  with  the  surrounding  atmosphere;  and 
thus  the  internal  temperature  does  not  rise.     But  when  the 
air  is  as  warm  as,  or  even  warmer  than,  the  body,  this  transit 
of  heat  outward  is  not  so  manifest,  yet  it  is  equally  certain. 

441.  The  skin  not  only  affords  a  passage-way  for  the  heat 
to  go  out,  as  through  any  dead  substance,  but  it  has  an  active 
power  to  furnish  the  means  of  carrying  off  the  surplus  heat, 
when  it  would  otherwise  accumulate  in  the  body.     The  skin 
is  constantly  preparing   and  throwing  the  perspiration  upon 
its  surface,  where  it  is  usually  converted  into  vapor  and  ab- 
sorbed by  the  atmosphere.     This  change  of  the  perspiration 
from  a  fluid  to  a  gaseous  form  —  from  water  to  vapor — is 
effected  by  the  addition  of  heat,  (§  416,  p.  177,)  which  is 
absorbed  from  the  body,  and  therefore  cools  it.     This  perspi- 
ration is  most  abundant  in  warm  weather,  when  the  air  can 
absorb  the  most,  and  causes  the  greatest  cooling  when  it 
is  most  needed.     It  is  a  common,  and  by  no  means  an  un- 
founded notion,  that  one  is  cooled  and  refreshed,  in  summer, 


ANIMAL    HEAT.  189 

by  drinking  a  cup  of  hot  tea.  The  tea  excites  the  perspira- 
tion, which  creates  the  necessity  of  evaporation ;  and  this  is 
done  very  much  at  the  expense  of  the  heat  of  the  body,  which 
is  thereby  cooled.  All  the  insensible,  and  most  of  the  sensi- 
ble perspiration  is  converted,  on  the  skin,  into  vapor ;  and, 
by  this  conversion  of  liquid  into  vapor,  a  large  portion  of  the 
excess  of  heat  is  carried  out  of  the  body,  and  the  standard 
of  the  internal  temperature  is  preserved. 

442.  This  evaporation  was  very  rapid  in  Sir  C.  Blagden's 
experiment,  (§  402,  p.  172 ;)  consequently,  the  temperature 
of  his  body  was  kept  down  to  about  its  usual  standard,  which 
was    162°    below   that   of   the    surrounding    air    which   he 
breathed.     He  received  dry  air  into  his  lungs  heated  to  260°, 
but  when  it  went  out,  it  was  cooled  down  nearly  to  98°  ;  and, 
when  he  breathed  this  air  upon  his  skinrit  felt  cold,  instead 
of  warm,  as  it  usually  does. 

443.  By  the  beautiful  adaptation  of  Nature's  supply  to  her 
wants,  the  animal  body  is  kept  cool  in  the  summer  and  warm 
in  the  winter.     The  greater  appetite  and  greater  desire  for 
animal  food,  supply  more    carbon    and    hydrogen,  and    the 
density  of  the  air  supplies  more  oxygen,  and  consequently 
a  greater  fire  is  maintained,  in  the  cold  season,  and  in  cold 
climates,  than  in  warm  seasons,  and  in  hot  climates,  when 
and  where  the  appetite  craves,  and  the  stomach  digests,  vege- 
table diet,  which  gives  less  fuel,  and  the  atmosphere  affords 
less  oxygen  for  the  support  of  the  combustion. 

444.  It  is  this  greater  supply  of  internal  heat,  and  the 
lesser  cooling  by  evaporation  from  the  surface,  that  give  us 
what  is  called  the  winter  constitution ;  and  the  diminished 
internal    fire,   and  increased   evaporation    of  the   perspired 
fluids,  give  us  the  summer  constitution.     By  these  means,  the 
body   is    able  to  endure    a   greater  degree  of  cold    in    the 
winter,   and  in    the  climate   of  the   polar   regions,  than  in 
the    summer,    and  in  the  tropical   countries;    and   we  can 
bear  a  greater  degree  of  heat  in  the  summer  and  in  warm 
climates,  than   in  the  winter  and   in   cold   climates.     That 
degree  of  cold  which  we  bear  without  discomfort  in  January, 


190  PHYSIOLOGY    AND    HEALTH. 

is  almost  intolerable  in  August.  We  are  sometimes  nearly 
overcome,  at  least  languid,  with  the  heat  of  a  thawy  day  of 
February,  when  the  thermometer  is  no  higher  than  40°. 
But  we  are  chilled  with  the  air  of  the  same  temperature  in 
July.  For  this  reason,  we  need  to  have  our  sitting-rooms 
somewhat  warmer  in  the  summer  than  in  the  winter.  An 
ice-house  is  a  sufficiently  warm  and  comfortable  place  for  a 
man  to  work  in  while  storing  ice  in  the  winter,  but  it  is 
chilly  and  often  dangerous  to  those  who  enter  it  in  the  sum- 
mer to  take  ice  away. 

445.  To  demonstrate  how  much  more  rapidly  the  heat 
passes  away,  and  how  much  less  power  of  resistance  to  cold 
the  animal  body  possesses,  when  it  is  under  the  influence 
of  its  summer,  than  when  under   the  winter   constitution, 
Dr.  Edwards,  of  Paris,   took    several    sparrows   from    their 
warm  rooms,  in  the  month  of  February,  and  put  them  in  a 
cage  surrounded  by  ice,  where  the  temperature  was,  at  the 
highest,  32° ;  after  remaining  there  three  hours,  they  had 
cooled  less  than  2°.     He  tried  the  same  experiment  in  the 
month  of  July,  with  the  same  conditions  and  in  the  same 
time;  the  sparrows  lost  21°  of  heat.* 

446.  We  gradually  pass  from  the  intensity  of  summer's 
heat  through  the  autumn  to  the  severity  of  winter's  cold,  and 
back  again  through  the  spring ;  and  as  each  of  these  oppo- 
site seasons  comes   upon  us,   we   receive   the   constitution 
adapted  to  it,  and  endure  the  extremes  of  temperature  with- 
out  suffering.     But  we  cannot   leap  from   the   one  to  the 
other  with  impunity.     A  resident  of  Massachusetts  would  be 
enervated  by  suddenly  arriving  in  the  West  Indies  in   the 
winter ;  and  if,  after  residing  under  the  equator  for  a  season, 
he  should  as  suddenly  return  to  Boston  in  January,  he  would 
suffer  from  the  cold. 

447.  The  dwellers  in  warm  houses,  and  the  workmen  in 
warm  shops,  retain   the  summer    constitution   through    the 
winter  more  than  the  out-of-door  laborers,  and  cannot  bear 

*  Influence  of  Physical  Agents  on  Life,  Part  III.  Chap.  III. 


THE    SKIN.  191 

cold  as  well  as  they  do  without  suffering,  and  therefore  need 
more  clothing  when  exposed  to  the  same  temperature.  A 
shoemaker  or  student,  going  from  his  warm  shop  or  room 
and  taking  the  outside  seat  of  the  stage-coach,  by  the  side  of 
the  driver,  in  winter,  must  wear  thicker  garments  than  his 
companion  who  is  daily  exposed  to  the  weather ;  if  he  does 
not  do  so,  he  will  suffer  more  than  the  coachman.  Those 
who  live  in  houses  heated  by  furnaces,  in  which  all  the 
entries  and  rooms  are  more  or  less  warmed,  and  who  seldom 
go  abroad,  hardly  receive  the  winter  constitution  in  the 
proper  season,  and  cannot  bear  exposure  to  the  open  air 
without  much  additional  clothing. 


PART   V. 

THE    SKIN. 


CHAPTER   I. 

The  internal  Structure  needs  Protection — Skin.  — Cuticle;  thick 
ened  by  Friction  if  gradually  applied.  —  Blisters.  —  Corns. 

448.  THE  inner  framework  and  vital  machinery  of  ani- 
mals—  their  lungs,  heart,  and  blood-vessels — their  muscles, 
nerves,  and  digestive  apparatus  —  are  all  very  delicate,  and 
would  ill  bear  exposure  to  the  action  of  the  elements,  or  even 
the  contact  with  other  bodies.  They  are,  there  fore,  protected 
with  some  outward  covering,  which  is  different  in  different 
animals.  Yet,  in  all,  it  stands  between  these  organs  of  life 
and  the  external  world.  In  man,  and  in  many  other  animals, 
this  outward  covering  is  the  skin,  which  is  a  soft  and  pliable, 
and  yet  a  strong  membrane,  that  is  not  easily  injured  or  torn, 
does  not  suffer  from  contact  with  other  substances,  and  will 
bear  wide  variations  of  heat  and  cold. 


192  PHYSIOLOGY    AND    HEALTH. 

449.  The  outer  skin  (Fig.  XXVI.  a,  a)  or  cuticle,  covers  the 
body.     It  is  lifeless  and  insensible.     The  hangnails  of  the 
fingers,  the  peeling  of  the  iips  when  we  have  a  cold,  are  parts 
of  this  skin.    If  we  pinch  them,  we  do  not  feel  it.    So,  also,  we 
may  run  a  pin  through  this  skin  at  the  corners  of  the  fingers 
or  thumb,  or  trim  the  thickened  skin  of  the  heel,  and  suffer 
no  pain.     It  does  not  ache  with  the  cold  nor  suffer  with  the 
heat.    It  has  no  nerves  to  feel  nor  blood-vessels  to  give  it  life. 

450.  The    cuticle,    sometimes    called   the   scarf-skin,    ie 
formed  by,  and  grows  from,  the  true  skin  beneath  it,  and  is 
constantly  casting  off  its  surface  in  the  form  of  powdery  scales. 
But  it  is  as  constantly  renewed.     This  process  of  change 
never  ceases  in  health.     Sometimes  this  outer  layer  peels  off 
from  the  lips  in  case  of  a  cold,  or  from  the  roots  of  the  nails; 
but    soon    another  takes  its  place.     When  it  is  peeled  off, 
it  leaves  the  true  and  sensitive  skin  bare  and  tender.    But, 
when  it  is  cast  off  naturally  in  dead  scales,  it  leaves  a  layer 
behind,  which  protects  the  more  delicate  parts  beneath. 

451.  Over  the  whole  of  the  child,  and  on  the  parts  of  the 
Fio.  XXVI.      Skin  and  per.spira.tory  Apparatus  highly  magnified. 


a,  a,  Cuticle.  I        c,  c,  c,  Perspiratory  glands. 

6,  6,  True  skin.  d,  d,  d,  Perspiratory  tubes. 


THE    SKIN.  193 

adult  which  are  not  exposed  to  contact  with  other  bodies, 
and  especially  on  the  lips,  this  cuticle  is  thin  and  delicate. 
But,  whenever  it  is  exposed  to  the  elements  or  friction,  it 
becomes  thicker  and  tougher ;  for  any  friction,  if  moderately 
applied,  instead  of  wearing  it  out,  causes  it  to  grow  more 
and  more ;  the  under  skin  throws  out  more  of  the  matter 
that  forms  the  cuticle,  and  this  latter  is  thickened  and 
strengthened.  This  is  most  observable  in  the  sole  of  the 
foot  arid  palm  of  the  hand ;  the  more  they  are  used,  the 
thicker  and  harder  their  cuticle  becomes,  so  that  the  bare- 
foot boy  treads  on  the  rough  pavement  without  injury. 

452.  Though  the  cuticle  becomes  thick  and  hard  from 
friction  and  labor,  yet  these  must  be  applied  cautiously  and 
gradually,  otherwise  the  reverse  will  happen.    When  the  stu- 
dent or  clerk  undertakes  to  cut  wood,  or  rake  hay,  or  row  a 
boat,  for  several  successive  hours,  the  cuticle  of  his  palms, 
instead  of  growing  thick  and  hard,  becomes  thin  and  sore. 
The  outer  skin  may  be  worn  off,  or  it  may  separate  from  the 
other,  and  the  under  skin,  instead  of  throwing  out  more  mat- 
ter to  be  formed  into  cuticle,  throws  out  a  watery  matter, 
which  fills  a  little  sack  between  them,  and  forms  a  blister. 

453.  But  if  this  friction  had  been  applied  gradually,  and 
continued  for  a  long  time,  it  would  have  stimulated  the  inner 
skin  to  form  more  and  more  of  the  outer  or  scarf-skin t  to 
meet  the  want  and   the  pressure,   instead  of  throwing  out 
water,  and  causing  pain  and  soreness. 

454.  By  the  gradual  application  of  friction,  the  skin  be- 
comes so  fortified  with  this  thickened  outer  layer,  that  it  will 
bear  very  rough  usage  without  suffering;  so  that  the  hands 
of  the  stone-layer  and  of  the  mason  are  neither  scratched  nor 
inflamed  by  the  rough  stones,  nor  irritated  by  the  lime  in  the 
mortar.     In  the  same  way,  the  hands  of  the  blacksmith  and 
the  founder  become  accustomed  and  prepared  to  handle  very 
hot  and  rough  metals  without  being  burned  or  suffering  pain. 

455.  But  if  one  unused  to  labor  with  his  hands  attempts  at 
once  to  become  a  stone-layer  or  brick-mason,  he  would  soon 
find  the  tender  skin  of  his  hands  blistered  and  torn.     The 

17 


194  PHYSIOLOGY   AND   HEALTH. 

new  apprentice  in  a  blacksmith  shop  or  a  foundery  burns  his 
hands  in  doing  the  very  work  which  the  older  workmen  do 
without  any  suffering. 

456.  When  the  feet  are  pinched  by  new  and  very  tight 
shoes,  painful  pressure  is  made  upon  the  skin,  and  sometimes 
blisters  are  raised  in  walking.  But,  if  this  pressure  be  more 
gently  and  gradually  made,  and  long  continued,  the  cuticle 
becomes  thickened  on  the  prominent  joints  of  some  of  the 
toes,  by  the  formation  of  new  underlayers.  These  layers  are 
broad  at  the  top  and  narrow  at  the  bottom,  and  the  whole 
thickening  is  somewhat  wedge-shaped  or  conical,  with  its 
point  inward.  This  is  a  corn ;  and  the  shoe,  bearing  upon  it, 
presses  upon  the  tender  flesh  beneath,  often  producing  acute 
distress. 


CHAPTER   II. 

Cuticle  defends  true  Skin^from  external  Injury.  —  Nails,  Hoof,  and 
Horn.  —  Seat  of  Color.  —  True  Skin  has  many  Blood- Vessels  and 
Nerves. 

457.  THE  cuticle,  placed  between  external  objects  and  the 
true  skin,  protects  it  from  their  contact.  It  bears  their  hard 
usage,  but  suffers  no  pain.  By  means  of  this  protection,  we 
are  enabled  to  handle,  not  only  rough,  and  hard  substances, 
but  many  matters  which  would  be  poisonous  to  the  more  deli- 
cate skin  beneath.  The  dyer  or  the  chemist  holds  his  hands, 
if  the  outer  skin  is  unbroken,  in  strong  mixtures,  without 
pain  or  irritation ;  but  if  the  cuticle  is  broken  and  the  inner 
skin  bare,  great  pain  and  sometimes  disease  are  the  conse- 
quence. Physicians  often  examine  the  bodies  of  those  who 
have  died  of  putrid  diseases,  and,  if  the  scarf-skin  of  Ihe 
operator  is  entire,  no  bad  consequence  follows ;  but,  if  there 
be  the  least  cut  or  scratch  of  this  cuticle,  through  which  the 
poison  can  gain  access  to  the  under  skin,  very  severe  disorder, 
and  sometimes  death,  ensue.  Some,  who  thought  themselves 


THE    SKIN.  195 

safe  because  they  had  no  perceptible  wound,  and  therefore 
exposed  themselves  to  very  virulent  poison,  have  been  infect- 
ed by  the  poison's  insinuating  itself  through  the  very  slight 
rupture  of  the  cuticle  on  the  end  of  a  finger,  where  a  mere 
hangnail  had  been  raised. 

458.  Other  parts,  that  grow  out  of  this  cuticle,  have  the 
same  structure,  and  are  endowed  with  the  same  properties. 
The  nails  of  our  fingers  are  productions  from  this  membrane, 
condensed  and  made  firm.     Yet  they  have  the  same  power  to 
protect,  and  the  same  insensibility.    The  hoofs  of  horses,  the 
horns  of  cattle,  are  similar;  they  have  the  same  protective  and 
the  same  negative  character. 

459.  The  nail   grows  from  the   cuticle.     It  has  its  root 
(Fig.  XXVII.  c)  in  the  inner  layers  of  this  membrane,  and 
its  under  surface  is  closely  attached  to  the  true  skin.     It 
grows  from  the  root  forward. 

FIG.  XXVII.    Vertical  Section  of  the  Thumb  and  Nail. 

a,  Nail. 
&,  Cuticle. 

c,  Root  of  the  nail. 

d,  True  skin. 

/,  Fatty  matter  under  the  skin. 
g,  Bone. 

460.  The  hair  (Fig.  XXVIII.  6,  c,  &,)  is  composed  of  a  sub- 
stance  similar  to  that  of  the  cuticle.     It  takes  its  origin  in  a 
pulpy  bulb,  (Fig.  XXVIII.  d,)   which  is  situated  below  the 
true  skin,  (Fig.  XXVIII.  /.)     It  is  fed  by  an  artery,  (Fig. 
XXVIII.  «,)  which  supplies  it  with  the  material  of  growth. 
Within  the  skin,  it  is  a  tube  containing  a  pulpy  matter,  (Fig. 
XXVIII.  c.)     In  ill  health,  or  in  the  later  periods  of  life,  this 
nutriment  diminishes  and  the  coloring  matter  ceases,  and 
then  the  hair  is  white.     Still  later,  the  nutriment  entirely 
fails,  and  then  the  hair  falls  out,  and  the  aperture  in  the  skin 
closes. 

461.  The  cuticle  is  continually  casting  off  its  outward  layer 
in  the  form  of  little   scales,  so  minute  as  to  seem  like  dust ; 


196 


PHYSIOLOGY    AND    HEALTH. 
FIG.  XXVin.     Hair  highly  magnified. 


a,  Artery. 

5,  5,  Tubular  part. 

c,  Pulpy  part. 

d,  Pulpy  bulb. 

e,  e,  Cuticle. 
/,  True  Skin. 


the  form  of  the  scales  is  scarcely  visible,  except  on  the  head. 
This  scurfy  dust  is  constantly  gathering  upon  the  surface, 
and  needs  to  be  frequently  washed  off  with  soap  and  water. 
And  when,  after  a  long  neglect  of  this  duty,  we  rub  the  skin 
vigorously  in  a  warm  bath,  we  feel  this  matter  gather  in  little 
rolls  under  the  hand.  After  some  fevers,  this  skin  comes  off 
in  little  flakes,  like  scales  of  bran,  but  not  in  health,  except  on 
the  head.  The  loss  of  these  outer  layers  is  continually  sup- 
plied by  the  new  growth  of  layers  underneath  from  the  inner 
skin.  This  process  of  change  gives  the  scarf-skin  a  constant 
freshness  of  substance. 

4f>2.  The  cuticle  is  composed  of  several  layers  of  thin 
scales.  The  outer  and  the  oldest  are  transparent.  The  pig- 
ment cells,  which  are  the  seat  of  color,  are  situated  in  the 
innermost  ^nd  the  last-formed  layer  ofthe  cuticle.  The  con- 
tents of  these  cells  give  the  different  shades  to  the  various 
races  of  mankind,  and  to  various  individuals.  This  matter  is 
white  or  flesh-colored  in  the  European  and  North  American, 
black  in  the  African,  yellow  in  the  Mongolian,  and  copper- 
colored  in  the  American  Indian.  It  is  this  which  is  dark- 
ened or  tanned  by  exposure  to  the  sun,  and  bleached  by  pro- 


THE    SKIN.  197 

tection.     Carpenter  says,  "  What  has  been  termed  the  rete 
mucosum  is  simply  the  last-formed  portion  of  the  cuticle." 

463.  The  various  coloring  of  this  inner  layer  of  the  cuti- 
cle gives  to  some  animals  their  varied  hues  —  to  the  serpent, 
the  frog,  and  the  lizard,  and  some  fishes,  which  have  a  splen- 
dor of  hue  almost  equal  to  polished  metal.     Goldfish  and  the 
dolphin  owe  their  difference  of  color,  and  the  brilliancy  of 
their  hues,  to  the  color  of  this  layer  of  skin. 

464.  Underneath  the  cuticle  is  the  true*  skirt,  (Fig.  XXVL 
6,  &,)  the  seat  of  all  the  active  functions  of  the  cutaneous  mem- 
brane.   This  layer  is  a  dense  and  thick  membrane,  and  com- 
posed of  firm  and  strong  fibres,  that  are  interwoven  like  the  felt 
of  a  hat.    It  is  almost  filled  with  minute  blood-vessels,  so  many 
that  a  large  proportion  of  the  blood  of  the  whole  system  flows 
in   them.      If  we  cut  the  outer  skin,   no  -blood  flows,  be- 
cause  no  blood   is  there;    but  if  we  cut  through  that  and 
into  the  inner  skin,  we  cannot  fail  to  wound  some  of  these 
vessels. 

465.  In  health,  when  every  thing  goes  on  well  in  the  ani- 
mal body,  the  blood  is  properly  distributed  in  all  the  organs, 
and  each  receives  its  due  proportion;  then  it  flows  freely 
through  the  vessels  of  the  skin,  and  the  surface  is  florid  and 
the  cheek  is  rosy.     But  cold  contracts  the  cutaneous  vessels, 
and  lessens  their  capacity  for  blood.     The  cutaneous  circu- 
lation is  sometimes  influenced  even  by  the  state  of  the  mind 
and  the  affections:  the  blood  flows  more  abundantly  in  the 
capillaries  of  the  face  when  the  modest  youth  blushes,  or 
when  one  is  excited ;  and  it  is  easily  driven  away,  and  the 
cheek  turns  pale,  when  one  is  oppressed  with  fear,  or  is  over- 
come with  anxiety. 

466.  This   skin   is   furnished    with    a   great  quantity  of 
nerves,  for  it  is  endowed  with  an  exquisite  degree  of  sensi- 
bility to  pleasure  and  to  pain ;  and  it  is  also  the  seat  of  the 
sense  of  touch.    In  man,  the  nerves  are  more  abundantly  dis- 
tributed to  the  skin  than  to  the  other  organs.     But  those 
animals  which  are  covered  with  hair,  feathers,  or  scales,  have 


198  PHYSIOLOGY    AND    HEALTH. 

not  this  large  supply  of  cutaneous  nerves,  nor  this  acute 
sensibility  of  the  skin. 

467.  Underneath  this  skin  there  is  a  layer  of  fat,  which 
varies  in  thickness  in  different  parts  of  the  body.  It  is  very 
thick  in  the  palm  of  the  hand  and  the  sole  of  the  foot,  and 
affords  a  cushion  to  meet  the  pressure  that  comes  upon  those 
or  other  parts  that  need  this  support;  while  in  the  forehead 
and  on  the  back  of  the  hand  it  is  very  thin,  for  there  it  is  not 
needed. 


CHAPTER  III. 

Functions  of  the  Skin .  Exhalations  :  Perspiration.  —  Sensible  and 
insensible  Perspiration.  —  Quantity.  —  Experiment  at  Phoenix  Gas 
Works. 

468.  THE  skin  is  the  outlet  for  a  good  proportion  of  the 
waste  of  the  body.     Some  goes  off  in  the  form  of  carbonic 
acid,  some  in  the  oil,  but  the  greater  part  in  form  of  perspi- 
ration.    Sanctorius,  a  celebrated  medical    writer,  carefully 
weighed  himself  and  all  his  food,  and  drink,  and  excretions, 
daily,  for  thirty  years;  and,  after  all  this  observation,  he  con- 
cluded that,  of  every  eight  pounds  which  were  taken  into  his 
system  each  day,  five  passed  out  through  the  skin. 

469.  Seguin,  a  philosopher,  weighed,  and  then  enclosed 
himself  in  a  bag,  which  was  glazed  so  as  to  prevent  the  per- 
spiration from  passing  through  it.     He  found  that  the  largest 
quantity  of  perspiration  that  passed  off  in  a  day  was  four  and 
a  half  pounds,  and  the  smallest  quantity  was  twenty-four  and 
three  quarter  ounces ;  the  medium  was  thirty-three  ounces. 

470.  This  is  the  insensible  perspiration ;  for,  although  it 
amounts  to  about  two  pints  a  day,  it  is  not  usually  percepti- 
ble; it  passes  off  in  such  minute  portions,  and  is  so  com- 
pletely dissolved  in  the  air,  that  we  do  not  perceive  it.    Yet 
it  can  be  perceived  by  holding  the  hand,  apparently  dry,  near 


THE    SKIN.  199 

a  cold  mirror,  which  will  condense  the  invisible  vapor  and 
soon  be  covered  with  a  slight  dew ;  or  if  we  put  the  hand 
into  a  large  tumbler  or  glass  pitcher  previously  wiped  dry, 
and  wind  a  towel  about  the  wrist,  so  that  nothing  can  pass 
out  at  the  mouth  of  the  glass,  we  shall  then  soon  see  the 
moisture  gather  upon  the  inner  surface.  This  can  be  noth- 
ing more  than,  the  condensed  exhalation  from  the  hand. 

471.  This  is  called  the  insensible  perspiration,  in  distinc- 
tion from  the  sensible  or  visible  perspiration,  which  flows  in 
drops  from  the  skin  when  we  are  excited  or  are  unusually 
warm.    The  insensible  perspiration  never  ceases  to  flow  dur- 
ing health ;  and  under  all  circumstances,  if  the  skin  is  in  a 
good  condition,  it  is  not  interrupted.     But  the  sensible  per- 
spiration flows  only  occasionally,  and,  though  more  abundant 
sometimes  than  the  other,  yet  the  whole  amount  is  much  less. 
In  the  cold-blooded  animals,  —  the  toad,  serpent,  &,c.,  —  the 
insensible  is  six  times  as  great  as  the  sensible  perspiration. 
The  difference  in  man  is  not  so  great  as  this,  yet  it  is  con- 
siderable. 

472.  The  sensible  perspiration  —  the  sweat  —  is  at  times 
very  great,  and  occasionally  we  saturate  our  clothing  with  it 
in  a  very  short  period.     Some  experiments  were  performed, 
and  observations  made,  at  the  Phcenix  Gas  Works,  in  London, 
Nov.  18,  1836,  to  determine  how  large  a  quantity  would  be 
thus  thrown  out  from  the  body  under  favoring  circumstances, 

473.  "  Eight  of  the  workmen  regularly  employed  at  this 
establishment  in  drawing  and  charging  retorts  and  in  making 
up  the  fires,  which  labor  they  perform  twice  a  day,  commonly 
for  the  space  of  one  hour,  were  accurately  weighed  in  their 
clothes  immediately  before  they  began  and  after  they  had 
finished  their  work.     On  this  occasion,  they  continued  at 
their  work  exactly  three  quarters  of  an  hour.     In  the  inter- 
val between  the  first  and  second  weighing,  the  men  were 
allowed  to  partake  of  no  solid  or  liquid,  nor  to  part  with  either. 
The  day  was  bright  and  clear,  with  much  wind.     The  men 


200  PHYSIOLOGY    AND    HEALTH. 

worked  in  the  open  air,  the  temperature  of  which  was  00° 
Fahrenheit.     The  barometer  was  29°  25'  to  29°  4'." 

474.    These  eight  men  lost,  during  these  three  fourths  of 
an  hour,  by  perspiration  from  the  skin,  various  quantities. 


The  first  lost  2  Ibs.  8  oz. 
second,   2  "    9  " 
third,      2  "  10  " 
fourth,    3  "    6  " 


The  fifth  lost  3  Ibs.  12  oz. 
sixth,       3  "    14  " 
seventh,  4    "      2  " 
eighth,    4   "      3  " 


The  average  loss  of  all  was  3  Ibs.  6  oz.* 

475.  This  constant  perspiration,  and  the  exhalations  from 
the  lungs,  maintain  the  permanency  of  the  weight  of  man ; 
so  that,  although  he  eats  and  drinks  from  four  to  six  pounds 
a  day,  his  body  at  night  weighs  no  more  than  on  the  day 
before ;  and,  if  one  man  eats  and  drinks  more  than  another, 
he  has  more  pulmonary  and  cutaneous  excretions,  and  the 
superabundance  is  thus  carried  away. 

476.  This  whole  amount  of  cutaneous  exhalations,  sensi- 
ble and  insensible,  will  average  about  the  same  in  a  healthy 
individual,    from/    day   to   day   or    from    month    to   month. 
Yet  there    are   many  circumstances   that   cause  it  to  vary. 
Climate  and  season  influence  it ;  it  is  more  in  summer  than 
in  winter;  philosophers  estimate  it  to  be  forty  ounces  in  the 
south,  and  twenty  ounces   a  day  in  the  north  of  Europe. 
Active  exercise  —  running,    hard    labor  —  will  increase  it, 
and  make  the  sweat  visible,  so  as  to  run  abundantly  in  drops. 
Unusual  quantities  of  clothing  prevent  the  radiation  of  heat, 
and  cause  it  to  accumulate ;  the  skin  then  becomes  warmer, 
until  an  increase  of  perspiration  occurs  and  relieves  by  its 
evaporation. 

•  Smith's  Philosophy  of  Health,  Vol.  II.  pp  391, 393. 


THE     SKIN.  201 


CHAPTER   IV. 

Perspiration  differs  in  various  Temperatures.  —  More  in  dry  than  in 
moist  Air Prepared  in  Glajids  for  the  Purpose.  —  Some  Ani- 
mals do  not  perspire  j«S  Oily  Excretions  from  the  Skin.  —  Tight 
Clothing,  Hats,  &c.,  prevent  Removal  of  these  Excretions. 

477.  This  perspiration   differs  in   various   conditions  of 
the  atmosphere.    .Heat  increases  the  activity  of  the  cutane- 
ous blood-vessels,  and  the  perspiratory  action,  and  also  the 
capacity  of  the  air  to  receive  vapor.  (§  349,  p.  152.)     Evapo- 
ration is  therefore  more  rapid  in  warm  than  in  cold  weather. 
A  moving  atmosphere  brings  to  the    body  a  constant  suc- 
cession of  layers  of  dry  air,  which  absorb  the  moisture  more 
rapidly.     The  perspiration  is  therefore  mere  free  in  a  windy 
than  in  a  still  day;  and,  if  the  wind  is  very  dry  and   hot, 
this  evaporation    is   still    further    increased.      The   sirocco, 
which  comes  over  Sicily  from  the  south,  is  so  dry  and  hot  as 
to  produce  in  the  skin  a  parching  and  painful  dry  ness,  and 
sometimes  excites  disease. 

478.  When  the  air  is  saturated  or  loaded  with  moisture, 
the  evaporation  is  checked,  and  the  perspiration  is  not  car- 
ried   off  so  freely ;     and  sometimes  this  interruption  causes 
a  serious  disturbance  and  burden  to  the  system.     The  waste 
that  is  carried  off  through  the  skin  gives  important  relief  to 
the  whole  body,  and,  if  this  is  interrupted,  oppression  follows, 
and  the  frame  is  languid.     In  some  of  the  sultry  dog-days, 
we  are  languid,  because  the  atmosphere,  being  already  filled 
with  vapor,  does  not  carry  off  the  watery  exhalations  of  the 
skin,  and  relieve  the  body.     From  this  cause,  internal  dis- 
eases  prevail  more    in  low    and  damp   situations   of  warm 
climates  than  in  dry.     On  the  banks  of  the  southern  and 
western  rivers,  this  is  most  painfully  manifested. 

479.  In  this  work  of  perspiration,  the  inner  skin  performs 
all  the  active  duty.     It  not  only  throws  this  fluid  out,  but  it 
originally  forms  it  out  of  the  elements  which  are  found  in 
the  blood.     This  work  of  formation  is  done  in  little  glands 


202  PHYSIOLOGY    AND    HEALTH. 

which  are  placed  (Fig.  XXVI.  c,c,e,)  just  beneath  the  skin; 
and  the  perspired  fluid  is  carried  from  each  one  of  them  to 
the  surface,  through  a  minute  tube  which  is  attached  to  the 
gland,  and  leads  outward  (Fig.  XXVI.  e?,f/,d,)  There  are  three, 
thousand  five  hundred  and  twenty-eight  of  these  little  tubes 
on  each  square  inch  in  the  palm  of  the  hand,  and  twenty- 
eight  hundred  on  each  square  inch  throughout  the  whole 
body,  making  seven  millions  of  perspiratory  tubes  on  a  man 
of  average  size. 

480.  The  power  of  relieving  the  body  of  its  superfluous 
matter  or  moisture  by  perspiration  is  not  common  to  all  ani- 
mals..   Men   and  horses  sweat,  and   thus  find   an  outlet  for 
these  matters,  and  for  the  excess  of  heat.      But   dogs   have 
no  such  means  of  relief;  when  they  are  heated  by  exercise, 
they  loll  their  tongues,  and  the  evaporation  from  their  sur- 
face  aids  in  the  cooling  process.     Cattle,  when  heated  in 
the  summer,  effect  the  same  purpose  in  the  same  manner. 

481.  There  are   other   secretions   of  the   skin  beside   the 
watery  perspiration.     The  skin  is  soft  and  oily,  it  is  supple, 
and  in  health  it  is  never  dry  and  hard.     To  produce  this 
condition,  there  are  numerous  little   glands  placed  within 
the  skin,  whose  business  it  is  to  gather  out  of  the  blood  the 
elements  of  an  oily  matter,  and  with  them  compound  this 
substance,  and  then  throw  it  out  upon  the  surface.     If  the 
preparation  of  this  oil  is  checked,  the  skin  is  dry  and  hard  ; 
but,  when  this  work  is  well  performed,  the  skin  is  soft  and 
supple;  and  pleasant  to  the  touch.     "  It  is  this  fluid  which 
soils  the  linen,  and   which  causes  the  water   to  collect  in 
drops,  when  we  come  out  of  the  bath."     These  oil-glands  are 
more  abundant  in  the  face  and  in  other  parts  exposed  to  the 
air,  and  in  the  arm-pits,  &>c.,  where  one  part  of  the  skin  comes 
in  contact  with  another.     But  through  all  the  skin  there  are 
enough  to  keep  the  surface  soft,  and  in  a  natural  condition. 

482.  This  oily  secretion   is  sometimes  odorous,   and  in 
some  parts  unpleasant  to  the  smell,  and  even  in  some  men 
fetid.     It  is  more  so  under  the  arms  than  elsewhere ;  but  in 
some  persons  the  whole  surface  throws  out  an  offensive  mat- 


THE    SKIN.  203 

ter.  This  odor  is  not  the  same  in  all  persons ;  it  is  said  that 
each  one  has  his  own  peculiar  smell,  by  which  the  dog  can 
scent  his  master  at  a  great  distance. 

483.  These    excretions   are   intended    to    be   carried,   not 
only  out  of,  but  away  from,  the  body.     If  suffered  to  remain, 
they  are  mixed  with  the  dust  in  the  air,  and  the  particles  of 
th'e  scarf-skin  that  scale  off;  and  they,  together,  form  a  thick, 
crusty  matter,  which  fills  the  pores  and  interrupts  the  trans-" 
mission  of  the  natural  fluids.     Then  the  skin  becomes  com- 
paratively stiff  and  hard,  and  loses  its  suppleness  and  agreeable 
feeling,  and  is  also  more  liable  to  suffer  from  the  effects  of 
cold.     The   perspiration   is   usually  carried    away  by  mere 
evaporation.     If,  therefore,  it  have  sufficient  access  of  air, 
it  will  generally  be  removed. 

484.  The  air  is  an  important  agent  in+  the  action  oj  the 
skin.     It.  gives  it  oxygen,  and  takes  from  it  some  carbonic 
acid.     It  removes  the  perspiration  and  some  of  its  superflu- 
ous oil.     It  is  necessary,  then,  that  the  air  should  reach  the 
body.     For  this  purpose,  the  clothing  should  be  loose  and 
porous.     Tight  clothing,  water-proof  dresses,  oil-cloth,  India 
rubber  garments,  glazed   coats,  and  even  leather  clothing, 
prevent  the  access  of  air,  and  the  transpiration  of  the  per- 
spired fluids ;  and,  inasmuch  as  they  thus  interfere  with  the 
functions  of  the  skin,  they  are  unhealthful,  and  improper  to 
be  worn.     India  rubber  shoes  retain  the  perspirationj  and 
the  feet  that  wear  them  are  often  wet.     It  is  a  common  com- 
plaint that  glazed  caps  worn  in  summer,  however  light  they 
may  be,  make  the  head  ache.     This  is  caused  by  the  close- 
ness of  their  texture,  which  prevents  the  free  passage  of  the 
vapor.     The  cap  fits  so  closely  to  the  head,  that  no  vapor 
can    escape,   and  its  impervious   texture   offers    no  avenue 
through  which  the  perspiration  can  pass  away. 

485.  For  the  same  reason,  hats  made  of  felt  are  too  close 
for  health  and  comfort.     Ventilated  hats  are  made  on  true 
physiological  principles,  because  they  allow  the   cutaneous 
excretion  free  passage  outward.     If  a  tight  felt  hat  is  worn, 
it  is  better  to  be  sufficiently  large  to  afford  room  for  much 


204  PHYSIOLOGY    AND    HEALTH. 

of  this  vapor  to  escape.  And  even  then  we  find  great  relief 
from  frequently  taking  off  the  hat  to  air  the  head,  or  rather 
to  air  the  hat  itself,  by  letting  the  enclosed  air,  which  is 
saturated  with  vapor,  pass  away,  and  fresh  air  take  its  place. 


CHAPTER  V. 

Connection  between  the  Skin  and  the  internal  Organs.  —  Stomach, 
Lungs,  Muscles,  &c.  —  Effects  of  Cold  on  different  People  va- 
rious. 

486.  There  is   a    very   intimate   connection    between   the 
skin  and  the  internal  organs  of  the  body.     The  blood  flows 
from  one   common  centre  through  various  channels  to  the 
minute  vessels  of  the  skin,  and  all  the  parts  included  within 
it.     If  the  outer  vessels  are  closed,  and  the  circulation  is  in- 
terrupted there,  the  blood  must  flow  in  greater  abundance 
into  the  inner  vessels.     On  the  contrary,  if  the  inward  flow 
is  impeded,  it  must  find  passage  outwardly.     In  either  case, 
the  balance  of  the  circulation  is  disturbed,  and  the  over- 
burdened part   is  disordered.     If  we   expose   ourselves   to 
sudden  or  long-continued  cold,  the  surface  becomes  chilled, 
the  cutaneous  vessels  contracted,  the  perspiration  checked, 
and  then  some  of  the  internal  organs  bear  the  burden  which 
usually  belongs  to  the  skin.     The  check  of  the  perspiration 
is  not  the  cause  of  the  disturbance ;  it  is  merely  one  of  the 
consequences  of  the   previous  interruption  without,  and  a 
sign  of  other  troubles  within. 

487.  We  have  seen  the  influence  of  tea,  taken  into  the 
stomach,    upon    the   cutaneous   circulation    and    functions. 
(§441,  p.  188.)     Certain  medicines,  taken  into  the  stomnch, 
have  the  same  effect.     A  man   under  the  operation   of  an 
emetic  often  sweats  profusely.     Some  kinds  of  food,  —  such 
as  shell-fish,  —  when  eaten,  will  cause  the  skin  to  break  out 
with  the  nettle  rash.     In  some  cases  of  indigestion,  the  same 
effect  is  produced.     In   September,   1845,   I   saw    a   child 


THE     SKIN.  205 

which  had  suddenly  broken  out  with  this  rash,  from  eating 
indigestible  food.  Its  skin  from  head  to  foot  was  covered 
with  this  scarlet  eruption.  But,  as  soon  as  the  stomach  was 
relieved  of  its  disturbing  cause,  the  rash  departed,  and  the 
skin  resumed  its  natural  color. 

488.  The  lungs  and    the   skin   are   intimately   connected 
by  their  mutual    sympathies.     They  cooperate  together  in 
carrying  off  much  of  the  waste  of  the  body.     They  bear 
each  other's  burdens.     When  the  circulation  is  checked  in 
the  skin,  it  may  be  thrown  more  upon  the  lungs ;  and  an  in- 
crease of  the  flow  of  blood  in  the  skin  relieves  the  lungs 
when  they  are  oppressed.     Every  one  is  familiar  with  the 
character   and  operation  of  a  cold,  and   with  the   common 
remedy  of  a  sweating  process.     A  man  puts  on  a  thinner 
dress,  or  goes  into  a  colder  atmosphere^,  than  he  has  been 
accustomed   to.     The  cold    of  the  air    diminishes   the  ca- 
pacity of  the  blood-vessels  of  the   skin,  interrupts  the  cu- 
taneous   circulation,    and    checks    the    perspiration.      The 
balance  of  the  circulation  is  disturbed,   and  the  lungs  are 
compelled   to   receive   more   blood  than  usually  belongs  to 
them.     These  organs  are  then  oppressed,  and  the  breathing 
becomes    somewhat   difficult ;    or    the   blood-vessels  in  the 
mucous  or  lining  membrane  of  the  air-cells  and  air-tubes  of 
the  lungs  may  become  enlarged,  and  carry  more  blood,  and 
throw  out  more  mucus,  which  is  coughed  up.     The  sufferer 
then  takes  hot  teas,  or  other*  stimulating  remedies  that  excite 
the  cutaneous  arteries,  and  he  covers  himself  under  an  un- 
usual quantity  of  bed-clothing.     The  skin  then  is  heated ;  its 
arteries  are  enlarged  and  more  active,  and  carry  more  blood : 
the  balance  of  circulation  is  restored,  and   the  perspiration 
breaks  out  profusely ;  and  then  the  lungs  are  relieved. 

489.  A.   similar   connection   exists   between   the  skin   and 
digestive  organs.     In  summer,  and  in  warm  climates,  an  in 
terruption  of  the  cutaneous  circulation  more  frequently  dis- 
turbs the  organs  of  nutrition,  and  excites  them  to  excessive 
action,  and  produces  a  painful  disturbance  ;  and,  on  the  con- 
trary, the  restoration  of  the  external  circulation  and  action 

18 


200  PHYSIOLOGY    AND    HEALTH. 

is  one  of  the  means  of  relieving  the  internal  disorder.  Ex- 
posure to  cold  is  sometimes  followed  by  disturbance  in  the 
organs  of  locomotion,  and  then  we  have  rheumatism,  pain, 
and  sometimes  swelling  in  the  muscles  and  joints.  In  this, 
as  well  as  in  the  other  cases,  the  disorder  is  removed  when 
the  balance  of  circulation  is  reestablished;  for,  when  the 
natural  perspiration  and  the  other  cutaneous  functions  are 
restored,  the  .rheumatism  diminishes,  and  the  limbs  and 
muscles  become  easy. 

490.  We  thus  see  that  the  skin  stands  not  alone,  but  is 
intimately  connected  with  the  internal  apparatus  of  life,  and 
does  not  suffer,  without  their  sympathy,  nor  enjoy  the  full 
measure  of  health,  without  their  participation  in  a  greater 
or  less  degree. 

491.  Persons  differ  in  the  degree  and  distribution  of  their 
health  and  strength ;  all  their  organs  and  systems  may  not 
have  the  same  power  of  action,  or  of  resistance  to  disturbing 
causes.     In  one    man  the  lungs,  in  another  the  organs  of 
locomotion,  and  in  a  third  the  digestive  apparatus,  and  in  a 
fourth  the   nervous  system.,  may  be  weaker  than  the  other 
organs.     It  is  the  weaker  internal  organ  that  is  in  the  most 
danger  of  suffering,  when  the  balance  of  circulation  is  dis- 
turbed.    Several  men  may  be  exposed  to  a  storm  together, 
and  all  may  be  drenched  with  rain  and  chilled.     In  all,  the 
cutaneous   circulation    is   disturbed,    and    the    perspiration 
checked,   the  blood  is   thrown,  inward,  and  some   internal 
derangement  may  follow.     But  this  differs  according  to  the 
previous  state  of  the  constitution.     One  of  these  men  takes  a 
cold  in  his  lungs,  the  second  is  attacked  with  a  pleurisy,  the 
third  with  a  disorder  of  the  digestive  organs,  the  fourth  with 
rheumatism,  the  fifth  has  a  fever,  the  sixth  a  headache,  while 
the  seventh  has  sufficient  vigor  of  constitution  to  resist  the 
internal  disturbance,  and  to  produce  immediate  reaction  in 
the  vessels  of  the  skin,   and  restoration  of  all   its  healthy 
functions. 

492.  There  are  many  conditions  of  the  body  that  affect 
the  insensible   as   well    as  the    sensible   perspiration.      All 


THE    SKIN.  207 

diseases  that  prevent  the  circulation  in  the  skin  interrupt 
the  flow  of  this  fluid.  In  some  of  the  stages  of  fever,  the 
skin  is  dry  and  parched.  But,  without  disease,  the  perspira- 
tory action  is  never  stayed,  so  that,  whenever  we  find  the 
skin  dry,  we  rhay  be  assured  that  all  is  not  right  in  the 
body. 


CHAPTER   VI. 

Skin  is  an  Absorbent.  Food  and  Drink  sometimes  taken  into  the 
Body  through  the  Skin.  —  Medicines.  —  Contagion.  —  Poisons 
absorbed  by  the  Skin.  —  Absorption  more  active  in  the  Night  than 
in  the  Day. 

493.  The,  skin  has  other  duties  to  perform,  besides  that 
of  carrying  off  the  waste  of  the  body  ;  it  is  an  absorbent  as 
well  as  an  exkalent.     In  certain— conditions,  it  takes  some 
matters  into  the  body,  while  it  throws  others  out.     But  this 
is  not  usually  done  in  a  period  of  health ;  it  is  rather  when 
in  a  state  of  disease.     Nevertheless,  absorption  is  not  always 
indicative  of  disorder.     It  may  be  used  to  prevent  or  relieve 
derangement  of  the  system.     It  is  the  most  active  when  the 
fluids  of  the  system    are  reduced    in   quantity,   and    when 
nutrition  is  not  well  sustained. 

494.  Sailors,  when  destitute  of  fresh  water,  wear  their 
clothes  wet  with  sea-water.     Then  the  skin  absorbs  and  car- 
ries some  of  this  fluid  into  the  body ;  and  thus  their  thirst  is 
allayed,  and  sometimes  entirely  relieved.     Dr.  Currie  relates 
a  case  of  a  patient,  who,  from  disease  of  the  throat,  was 
unable  to  swallow  any  thing,  and  was  therefore  in  danger 
of  immediate  death  from  starvation.     His  flesh  was  rapidly 
wasting  away;  he  suffered  extremely  from  thirst,  and  was 
nearly  exhausted.     While  in  this  state  of  suffering,  he  was 
placed,  night  and  morning,  in  a  bath  of  milk  and  water. 
After  this  was  begun,  his  body  ceased  to  waste ;  and,  while 


208  PHYSIOLOGY   AND    HEALTH. 

this  course  was  pursued,  he  maintained  his  weight,  and  the 
thirst  ceased  to  be  troublesome.  In  this  case,  the  skin 
absorbed  sufficient  fluid  and  nourishment  to  maintain  life. 

495.  One  of  the  men  who  were  subjected  to  the  sweat- 
ing experiment  of  Dr.  Smith  (§§  473,  474,  p.  199)  —  the  one 
who  lost  two  pounds  and  fifteen  ounces  —  went  into  a  hot 
bath  at  95°,  where  he  had  remained  exactly  half  an  hour.     He 
was  reweighed  on  coming  out  of  the  bath ;    and  then  it  was 
found  that  he  had  gained  half  a  pound.      This   must  have 
been  by  the  absorption  of  water.    In  the  case  of  Ann  Moore, 
(§  97,  p.  50,)  there  was  some  matter  constantly  passing  off 
through  the  lungs,  and  doubtless  some  perspiration.     Yet, 
for  years,  she  took  nothing  through  the  mouth  but  a  little 
tea,  and  not  enough  of  this  to  sustain  life  and  to  meet  the 
wants  of  respiration,  and  yet  she  did  not  waste  away.     The 
body  must  have  been  sustained  by  matter  which  was  absorbed 
from  the  atmosphere  through  the  skin. 

496.  Other    substances   beside    fluids    may    be   thus    ab- 
sorbed.   The  odor  of  camphor  or  of  garlic  may  be  perceived 
in  the  breath,  when  a  plaster  of  one  of  these  substances  is 
worn  upon  the  skin.     Medicines  are  sometimes  thus  intro- 
duced into  the  system ;  some  liniments  may  be  rubbed  into 
the  skin,  and  entirely  absorbed.     Antimony  rubbed  over  the 
stomach  is  said  to  produce  vomiting.     Mercury,  in  the  same 
way,  may  bring  on  salivation.     Men  at  work  in  lead  mines, 
or  in  an  atmosphere  of  lead  or  lead  paints,  are  often  troubled 
with  what  is  called  the  lead  colic,  from  the  absorption  of 
particles  of  lead  through  the  skin. 

497.  But  what  should  set  at  rest  all  doubt  of  the  absorb- 
ing power  of  the   skin    is   the  effect  of  contagion.      The 
slightest  quantity  of  matter  from  the  pustule  of  the  kine  pox, 
when  applied  to  the  inner  skin  under  the  cuticle,  excites 
disease  in  the  whole  system.      So  other  contagious  diseases  — 
such  as  small-pox  —  are  conveyed  by  the  bare  touch.     Even 
the  matter  of  the  latter  disease  which  may  be  rubbed  from 
the  skin,  and  lodged  on  the  clothing  or  the  bed,  will  be  ab- 


THE    SKIN.  209 

sorbed,  and  convey  the  disease  to  any  one  who  should  next 
sleep  in  that  bed  or  wear  that  garment  which  had  been  thus 
infected.  The  poison  of  dogwood  or  ivy  is  absorbed  by  the 
skin  of  the  susceptible,  if  they  but  touch  the  plant;  and  the 
disease,  being  excited  within  the  skin,  extends  beyond  the 
point  of  contact,  and  sometimes  over  the  whole  surface. 

498.  The  poison  of  bad  air  is  supposed  to  be  thus  ab-' 
sorbed.     In  marshy  countries,  where  the  exhalations  from 
the  earth   infect   the  atmosphere  with  the   seeds   of  fever 
or  other  disease,  the  people  whose  lungs  breathe,  and  whose 
surface  is  in  contact   with  this  air,  receive   the   poison   by 
the  absorbing  power  of  their  skin  and  their  air-cells 

499.  This  absorbing  power  is  more  active  at  night :  then 
contagion  of  disease  and  infection  of  bad  air  act  with  more 
readiness  and  vigor,  and  men  are  more  liable  to  be  attacked 
by  prevailing  epidemics  through  the   air,  or  by  contagious 
diseases  from  contact  with  those  already  diseased,  than  in  the 
daytime.     It  is  more  active  when  the  body  is  badly  nour- 
ished than  when  it  is  well  fed.     Hunger  and  thirst  increase 
the    absorbing   power   of   the    skin,    and    good    nutriment 
diminishes  it.     So  that  one  is  more  susceptible  of  disease 
before  than    after  breakfast,   (§113,  p.  56;)    and   cautious 
physicians  fortify  themselves  with  nourishment  in  the  morn- 
ing, before  they  visit  patients  who  are  suffering  from  epi- 
demic or  oontagious  diseases. 

500.  Any  poisonous  or  offensive  matter  in  contact  with 
the  surface  stimulates  the  cutaneous  absorbents.     The  nat- 
ural excretions  of  the  skin,  —  the  perspiration,  the  oil,  and  the 
dead  cuticle,  —  being  the  offensive  waste  of  the  body,  if  not 
removed  from  it,  excite  this  tendency  to  absorption ;   and 
when  they  are  not  washed  away,  or  are  confined  too  much  by 
impervious  clothing,  they  themselves  are  often  taken  back,  to 
irritate  and  disturb  the  system. 

18* 


210  PHYSIOLOGY    AND    HEALTH. 


CHAPTER   VII. 

Skin  Seat  of  Touch.  —  Sensibility  of  Skin  differs  in  different  Parts, 
and  in  different  Persons.  —  If  the  outer  Skin  is-  thick  or  foul,  the 
Sensations  of  the  inner  Skin  are  dull.  —  Sense  of  Touch  can  be 
cultivated  — Blind  have  acute  Sense  of  Touch. 

501.  The  sense  of  touch  is  situated  in    the   skin.     It  is 
not  in  the  cuticle,  which  is  insensible,  but  it  is  in  the  true 
or  inner  skin,  which  is  very  sensitive  and  exceedingly  alive 
to  pain,  and  suffers  from  contact  with  any  matter,  however 
soft  and  bland.     Strip  off  the  outer  skin  and  expose  the  layer 
beneath,  and  this,  which  before  was  comfortable  when  pro- 
tected, will  now,  in  its  nakedness,  ache  with  pain.    Even  the 
air  is  disagreeable  to  it.     But  this  sensibility  to  pain  is  un- 
equally distributed.     The  sensibility  to  contact,  or  the  acute- 
ness  of  the  sense  of  touch,  also  differs  in  the  various  parts  of 
the  skin.     Some   parts   are  more  plentifully  supplied  with 
nerves  than  others.     The  ends  of  the  fingers,  the  lips,  and 
the  face  of  man,  and  the  end  of  the  elephant's  trunk,  have 
more  nerves  and  more  sensibility  than  the  back  or  the  chest; 
these  and  all  other  uncovered  parts  have  more  than  the  head, 
which  is  covered  over  with  hair. 

502.  The   cutaneous  sensibility  is   as  unequally  distrib- 
uted as  are  the  nerves.     It  is  the  greatest  at  the  tip  of  the 
fingers,  and  the  least  in  the  scalp.     The  sensibility  of  touch 
is  more  acute  in  the  right  than  the  left,  but  the  sensibility 
in  regard  to  heat  is  greater  in  the  left  than  in  the  right  hand ; 
for.  "  if  the  two  hands  were  immersed  in  warm  water  of  the 
same  temperature,  that  in  which  the  left  was  plunged  would 
feel  the  warmest."     The  sensibility  differs  very  much  in  dif- 
ferent individuals,  so  much   "  that  that   which   amounts  to 
absolute  torture  in  one  is  a  matter  of  almost  indifference  to 
the  other."     The  sensibilities  are  more  acute  in  the  young 
than  in  the  adult,  and  in  the  latter  than  in  persons  of  ad- 
vanced life.     They  are  greater  in   the   female  than   in  the 
male;  in  the  sanguine  and  nervous  than  in  the  phlegmatic 


THE    SKIN.  211 

and  bilious  temperaments,  and  in  those  enfeebled  by  dis- 
ease, than  in  the  sound  and  robust."  * 

503.  The  facility,  with  which  cutaneous  sensations  are 
received,  depends  upon  the  condition  of  the  outer  skin. 
When  it  is  thick,  as  on  the  palm  of  the  hand  or  the  sole  of 
the  foot,  sensation  is  somewhat  interrupted.  The  seamstress 
finds  it  more  difficult  to  feel  and  distinguish  minute  differ- 
ences of  objects  with  the  fingers  with  which  she  uses  the 
needle  than  with  the  others.  The  difficulty  is,  not  that  the 
sensibilities  in  these  fingers,  as  in  the  palm  or  the  sole,  are 
more  blunted  than  in  the  others,  but  that  a  thicker  shield 
of  cuticle  stands  between  the  nerves  in  the  inner  skin,  and 
the  object  which  is  to  be  examined. 

594.  The  sense  of  touch  differs  very  widely,  not  only  in 
various  parts,  but  in  various  persons.  .Beside  the  natural 
and  original  differences  of  sensibility  from  organization, 
there  is  a  very  great  difference  owing  to  education ;  for 
this  sense  can  be  educated  to  a  very  high  degree,  so  that  one 
person  may  be  able  to  perceive  objects  and  characters  which 
another,  whose  sense  of  touch  is  less  cultivated,  could  not 
recognize. 

505.  It  is  a  remarkable  provision  of  a  benevolent  Provi- 
dence that,  when  one  sense  is  lost  or  impaired,  the  others 
become  more  acute,  so  as  to  compensate  in  a  good  degree  for 
the  defect.  Thus  the  blind  have  or  acquire  a  niceness  of 
touch  which  the  seeing  never  possess.  Their  method  of 
reading  is  a  singular  proof  of  the  extent  to  which  the  culti- 
vation of  the  sense  of  touch  may  be  carried.  Their  books, 
instead  of  being  printed  on  soft  paper,  and  with  colored  let- 
ters, are  printed  on  stiff  paper,  and  with  raised  letters.  Their 
pages  are  perfectly  white,  but  the  surface  is  not  smooth.  Their 
letters  stand  out  as  if  carved  in  wood.  The  blind  move  their 
fingers  over  these,  and,  by  the  sense  of  touch,  they  recognize 
the  shape  and  kind  of  each  letter  almost  as  readily  as  others, 
who  see,  recognize  letters  that  are  printed  with  ink.  It 

*  Wilson  on  the  Skin. 


212  PHYSIOLOGY    AND    HEALTH. 

is  interesting  to  notice  with  what  rapidity  these  sightless 
children  can  read.  They  must  of  course  perceive  one  letter 
at  a  time,  and,  at  the  end  of  each  word,  determine  what  the 
several  letters  spell.  Yet,  with  this  additional  mental  pro- 
cess, they  read  nearly  as  fast  as  we  do  with  the  use  of  oui 
eyes.  This  seems  very  easy  when  we  see  them  do  it ;  but  if 
we  shut  our  eyes,  and  then  apply  the  fingers,  not  to  a  whole 
word,  but  to  a  single  letter,  —  the  letter  #,  for  instance,  —  we 
shall  find  it  is  not  so  easy  for  the  untrained  to  decipher  the 
raised  marks.  If  we  further  attempt  to  read  a  word  or  sen- 
tence, we  shall  be  lost  in  the  mazes  of  indistinguishable 
characters. 

506.  The  blind  are  compelled  thus  to  cultivate  the  sense 
of  touch,  to  compensate  for  their  deficiency  of  sight.     But 
the  power  so  to  do  is  not  confined  to  them.     We  all  can  do 
the  same,  if  we  apply  the  same  diligence ;  and  this  we  could 
do  if  we  had  as  strong  a  motive  as  they  have.     The  cloth- 
dresser  learns  to  distinguish,  by  aid  of  the  sense  of  touch  in 
his  fingers,  the  qualities  oi  material,  or  minute  differences 
of  texture,  which  others  -cannot  detect.     The  miller,  in  the 
same  way,  detects  the  various  qualities  of  meal   and  flour, 
which  escape  the  notice  of  others.     In  a  great  many  of  the 
arts  of  life,  the  sense  of  touch  is  thus  educated  to  be  used 
for  minute  and  useful  purposes. 

507.  This  sensibility  is  blunted  by  several  causes.     Cold 
remarkably  diminishes  it.     Our  skin  is  numb  when  exposed 
to  a  very  low  temperature,  so  that  men   sometimes   cut  or 
bruise  themselves,  in  winter,  without  feeling  it;   and  the  first 
intimation  which  they  have  of  their  injury  is  the  sight  of 
their  flowing -blood.     This  sensibility  is  also  impaired  by  the 
natural  excretions  of  the  skin,  by  the  mixture  of  the  dead 
scarf-skin,  oil,  and  perspiration,  with  the  dust  and  dirt,  if  not 
removed  from  the  surface.     The  blind  man  will  wash  his 
fingers  before  he  attempts   to  read  his  raised  letters;   and 
the  cook  will  pass  through  the  same  process  when  she  leaves 
her  ordinary  work,  and  takes  up  her  fine  sewing. 


THE    SKIN.  213 


CHAPTER  VIII. 

Animal  Heat  permanent.  —  Skin  regulates  it.  —  Excess  of  Heat 
carried  off  by  Evaporation  of  the  perspired  Fluids.  —  Cold 
Sweats.  —  Sensations  of  Heat  and  Cold  comparative. 

508.  The  skin  is  itself  a  bad  conductor  of  heat ;  that  is, 
it  does  riot  allow  heat  to  pass  easily,  either  outwardly  or 
inwardly,  and  therefore  it  is  a  good  protector  against  high  or 
low  temperatures.     The  natural   and  usual   temperature  of 
the  body  is  98° ;  ..but  the  surrounding  air  is  often  at  100°  in 
summer,  and  afc-0  in  winter;   and,  in  some- extreme  climates, 
it  is  30°  warmer,  or  150°  colder,  than  our  bodies.     In  the 
experiments  of  Sir  Charles  Blagden,  (§  402,  p.  172,)  it  was 
more  than  160°  higher  than  the  standard  of  98°  ;  and  yet  in 
neither  case  is  the  heat  of  the  body  materially  changed.     In 
the  heated  room,  a  thermometer  placed  in  the  mouth  was 
hardly  raised,  and,  beyond  the  arctic  circles,  it  scarcely  tell 
below  our  usual  temperature. 

509.  There  is,  of  course,  a  constant  tendency  to  radiation 
of  heat  from  the  skin  when  the  air  is  colder  than  our  bodies, 
as  from  any  other  substance :  and,  on  the  other  hand,  there 
must  be  a  tendency  to  receive  heat  from  the  air  when  that 
is  warmer  than  the  body.     In  the  first  case,  in  cold  weather, 
more  internal  heat  is  produced,  (§  443,  p.  189,)  to  supply 
loss  from  increased  radiation.     In  warm  seasons,  the  evapo- 
ration of  the  perspiration  absorbs  the  excess  of  animal  heat, 
and    thus   the   equilibrium   of  the   internal  temperature   is 
maintained. 

510.  The  evaporation  of  the  cutaneous  fluids  is  the  outlet 
of  much  of  the  surplus  heat.  (§  441.  p.  188.)     Every  one  is 
familiar  with  the  fact,  that  a  wet  skin  is  colder  than  a  dry 
one,  because  the  evaporation  carries  off  more  of  the  heat. 
The  inhabitants  of  hot  climates  make  use  of  this  princi- 
ple, and  put  water  into  porous  jars,  the  surface  of  which  is 
constantly  wet  with  the  moisture  that  oozes  through;   and 


214  PHYSIOLOGY   AND    HEALTH. 

the  rapid  evaporation  of  this  cools  the  water  within.  Even 
ice  may  be  thus  produced.  We  are  therefore  cooler  when 
we  sweat.  Blagden  found  great  relief,  in  his  oven,  from  the 
profuse  perspiration  which  was  rapidly  evaporated. 

511.  The  cooling  power  of  the  air  is  influenced  by  other 
states  besides  its  temperature.     A  dry  atmosphere,   by  in- 
creasing evaporation,  cools  the  body  more  rapidly  than  air 
saturated  with  vapor.     Winds  have  the  same  effect.     Even 
if  the  air  is  warmer  than  the  body,  if  it  is  in  motion  and  dry. 
it  cools  us  ;  so  that  a  lady's  fan,  at  summer's  noon,  when  the 
thermometer  stands  at  100°,  two  degrees  warmer  than  the 
flesh,  affords  a   pleasant    coolness,  by  moving  the  air,   and 
hastening  the  evaporation.     So  slight  a  motion  of  the  air  is 
thus  perceptible  by  the  increasing  coolness,  that  men,  when 
they  cannot  distinguish  the  direction  of  the  wind  by  its  force 
upon  their  bodies,  or  even  by  the  movements  of  leaves  of 
trees,  often  wet  a  finger,  and,  holding  it  up  to  the  air,  dis- 
cern, by  their  sensations,  which  is  the  colder  side.      This 
determines  the  course  in  which  the  air  is  moving. 

512.  In  order  that  the'  skin  should  passively  permit  the 
heat  to  pass   off  by  radiation,  or  actively  throw  it  off  by 
perspiration,  it  must  itself  be  in  good  health.     It   must  be 
able  to  prepare  within  itself  just  as  much  fluid  as  will,  by  its 
evaporation,  carry  off  the  surplus  heat,  and  no  more ;  other- 
wise we  may  be  too  hot  or  too  cold. 

513  In  some  states  of  disease,  men  suffer  from  a  con- 
stantly'dry  and  parched  skin.  Their  flesh  burns  within,  and 
the  accumulating  heat  finds  no  outlet,  for  the  skin  affords  no 
relief.  In  other  disorders,  they  are  prostrated  with  a  pro- 
fuse and  cold  sweat.  The  skin  pours  out  the  perspiration 
like  water,  and  this,  by  evaporating,  creates  a  constant  and 
painful  demand  for  heat ;  and  then  the  patient  finds  it  im- 
possible to  keep  warm. 

514.  Although  it  is  through  the  sensibility  of  the  skin 
that  we  perceive  things  to  be  hot  or  cold,  yet  this  is  by  no 
means  an  exact  measurement  of  the  degree  of  heat;  for 
the  apparent  and  sensible  temperature  of  any  substance  is 


THE    SKIN.  215 

merely  relative  to  the  previous  sensations.  If,  after  we  have 
been  handling  snow,  we  take  a  piece  of  iron  heated  to  50°, 
it  feels  to  us  warm.  But  if  another,  who  had  been  holding 
his  hands  in  warm  water,  at  98°,  should  take  up  the  same 
iron  at  50°,  it  would  seem  to  him  cold.  If  one  should  come 
from  the  outer  air  of  a  cold  day  in  winter,  where  the  ther- 
mometer is  at  0,  and  enter  a  cellar  where  the  temperature  is 
at  50°  or  60°,  he  would  feel  a  pleasant  sensation  of  heat,  and 
call  the  cellar  warm.  But  if,  at  the  same  time,  another 
should  descend  from  his  parlor,  heated  to  70°,  into  the  same 
cellar,  he  would  complain  of  cold. 

515.  It  is  no  uncommon  circumstance  for  two  travellers 
to  meet  midway  on  the  side  of  a  high  mountain.     One  is 
coming  from  the  top,  where  snow  covers  the  ground  and  the 
air  is  wintry ;  the  other  is  going  up  from  fhe  valley  below, 
where  summer  reigns.     The   descending  traveller,  coming 
from  the  cold  region,  and  finding  the  air  warmer  than  that 
which  he  has  just  left,  complains  of  the  oppressive  heat,  and 
throws  off  his  woollen  clothes  and  puts  on  his  summer  gar- 
ments ;  while  the  ascending  traveller,  coming  from  another 
atmosphere,  much  warmer  than   the  present,  complains  of 
the  cold,  and   changes  his  summer  for  his  winter  clothing. 
Both  these  men  are  exposed  to  the  same  temperature,  but 
have  very  opposite  sensations. 

516.  Every  thing  which  depresses  the  power  and  energies 
of  life  diminishes  the  production  of  internal  heat,  (§  434, 
p.  186,)  and   also  lessens  the  protective  power  of  the  skin 
against  the  external  cold.     Under  the  influence  of  hunger 
and  fatigue,  and  the  consequences   of  exhausting  disease, 
and   when  overborne  by  the  depressing  passions  and  emo- 
tions —  grief,  despondency,  anxiety,  and  fear,  —  the  skin  has 
less  power  to  defend  us  from  the  extremes  of  heat  and  cold, 
and  we  are  then  more  uncomfortably  hot  in  high  tempera- 
ture, and  suffer  more  from  the  low.     But  the  contrary  hap- 
pens when  we  are  well-fed  and  fresh,  when  we  are  vigorous 
and  cheerful,  and  when  we  are  animated  with  hope  or  ex- 
hilarated with  confidence. 


210  PHYSIOLOGY    AND    HEALTH. 


CHAPTER  IX. 

Clothing  needed  to  prevent  excessive  Radiation  of  Heat.  —  Parts 
usually  clothed  need  more  Protection  than  others.  —  Habit  of 
Dressing  affects  the  Necessity.  —  No  positive  Law  for  the  Amount 
of  Clothing. 

517.  THE  skin  is  thus  shown  to  perform  three  offices.     It 
carries  off  much  of  the  waste  of  the  system,  by  means  of 
perspiration,  oil,  and  carbonic  acid.     It  absorbs  some  mat- 
ters from  the  atmosphere  and  other  contiguous  substances. 
It  regulates  the  transfer  of  heat  from  within  outward,  and 
prevents  its  coming  inward  from  without. 

518.  It  is  a  natural  question  to  ask,  whether  the  skin  can 
do  this  alone,  or  does  it  require  our  aid  to  enable  it  to  per- 
form these  functions  faithfully  and    successfully?     We  are 
so  much  the  creatures  of  habit,  we  have  been  so  accustomed, 
through  many  years,  and  even  from  generation  to  generation, 
to  cover  the  body  with  clothing,  that  it  is  not  easy  to  tell 
how  great  a  degree  of  cold  could  be  borne  upon  the  naked 
surface.     As  it  is,  there  are  not  many  days,  even  in  summer, 
when  we  should  feel  as  comfortable  as  we  now  do,  if  those 
parts  of  the  body  which  have  always  been  clothed  were  left 
unprotected. 

519.  Certain  it  is  that   the  heat  is  constantly  prepared 
within  the    animal    system ;    and  it  is  equally  evident  that, 
when' the  body  is  warmed  to  its  natural  and  usual  degree  of 
98°,  the  excess  beyond  that  must  pass  off.     As  much  is  then 
to  be  thrown  out  as  is  added,  and  this  is  done  mostly  through 
the  skin.     But  it  is  not  so  certain  that  the  skin  could,  un- 
aided by  clothing,  regulate  this  transmission  of  heat  so  ex- 
actly that  the  internal  temperature  would  not  vary  from  its 
usual  standard.     Whatever  the  natural  protective  power  of 
the  outer  surface  might  have  done,  if  we  and  our  fathers  had 
from  the  beginning,  lived  in  a  state  of  nature,  there  can  be 
no  doubt  that  we  and  all  civilized  men,  in  temperate  and 


THE    SKIN.  -  217 

colder  climates,  now  need  the  aid  of  clothing  to  protect 
ourselves  from  cold  during  most  of  the  year. 

520.  There  is  a  very  great  difference  in  the  present  pro- 
tective power  of  different  parts  of  the  skin ;  and  this  varies, 
also,  in  different  persons,  according  to  their  various  habits. 
The  air  is  seldom  so  cold  as  to  compel  us  to  cover  the  face, 
or  even  the  upper  part  of  the   neck.     These  parts  have 
always  been  exposed  to  the  severities  of  winter,  and  they 
have  borne  them,  and  do  now  bear  them,  without  suffering. 
But  the  chest  and  the  back  would  hardly  bear  the  open  ex- 
posure to  the  weather  of  the  warmest  day  of  the  summer, 
without  suffering  from  chill. 

521.  The  female  costume  usually  exposes  the  neck  and 
the  upper  part  of  the  chest,  and  even  sometimes  a  portion  of 
the  back  and  shoulders.     But  women  do  not  complain  of 
suffering  materially  from  this  exposure.     The  dress  of  men 
covers  the  entire  chest,  shoulders,  and  back,  and  most  of  the 
neck ;  and  they  seem  to  be  none  too  warm.     But  if  a  man 
accustomed  to  dre^ss  thus  should  expose  his  skin  as  women 
do,  or  even  if  he  were  to  leave  off  his  cravat,  after  wearing 
it,  in  winter,  he  would  immediately  feel  uncomfortably  cold ; 
and,  if  this  exposure  were  continued  for  any  length  of  time, 
he  would  so  change  the  balance  and  direction  of  the  circula- 
tion that  the  blood  would  be  thrown  inwardly  upon  the  lungs 
or  throat,  and  he  would  take  cold,  and  perhaps  severe  dis- 
ease would  follow. 

522.  The   North    American    Indian   wears    much    less 
clothing  than  his  civilized  neighbors.     While  we  cover  our- 
selves from  neck  to  feet,  and  leave  no  part  of  the  surface 
exposed,  the  Indian  is  satisfied  and    comfortable  with  his 
blanket  for  his  back  and  shoulders,  his  girdle  for  his  loins, 
and  his  moccasons  for  his  feet.     His  limbs  and  his  breast  are 
bare.     In  the  costume  of  the  Highlander,  who  lives  in  the 
northernmost  parts  of  Scotland,  the  kilt,  or  the  short  petti- 
coat, scarcely  meets  the  stockings ;  and,  as  he  wears  no  pan- 
taloons, his  flesh  about  the  knees  is  bare  and  exposed  to  the 
cold  of  his  severe  climate ;  and  yet  he  seems  to  be  as  com- 

19 


218  PHYSIOLOGY    AND    HEALTH. 

fortable  as  his  southern  neighbors,  whose  limbs  are  more 
carefully  protected. 

523.  There  is  a  great  difference  in  the  habits  of  clothing 
of  individuals.     One  always  wears  thick  clothing,  and  from 
the  first  approach  of  cold  weather  in   the  autumn"  till   the 
warmth  of  spring,  he  never  ventures  abroad  without  a  great 
coat ;  and  if  by  chance  he  is  compelled  to  go  out  without  this 
protection,  he  is  chilled,  and  perhaps  disordered  ;  while  others 
dress  much  lighter,  and  find  few,  perhaps  no  days  in  winter 
so  cold  as  to  require  any  such  extra  covering. 

524.  Some  men   never   wear  gloves  or   mittens;    others 
always  wear  the  warmest  they  can  obtain.     Some  wear  flan- 
nels next  to  their  bodies;    others  never  wear    any.      Some 
always  put  on  a  tippet  to  cover  the  neck  in  any  weather  in 
winter,  and  suffer  if  they  leave  it  off  before  the  warm  season 
returns;    others  wear  only  low  cravats,  or  even  none,  and 
suffer  no  more.     Men  wear  stout  boots  and  thick  stockings 
through  the  winter,  while  most  women  are  kept   apparently 
warm  with  worsted  or  cotton  hose,  and  shoes  as  thin  as  men 
wear  in  the  dryest  and  warmest  days  of  summer. 

525.  Thus  we  see  that  there  is  no  positive  and  fixed  law 
for  the  quantity  of  protection  which  we  should  give  to  the 
external  surface.     There  is  a  very  great  difference  in  man- 
kind in  this  respect,  without  a  corresponding  difference  of 
health  and  comfort.     This  is  due,  in    a   great  measure,  to 
difference  of  habit  of  clothing.      Men   cannot    change  this 
habit  suddenly  without  suffering ;   yet,   if  they  do  this  cau- 
tiously and  gradually,  they  may  nearly  reverse  their  habits, 
and  still  retain  their  health. 

526.  Those  who  accustom  themselves  to  wear  but  light 
clothing,  and  exercise  actively,  in  the  cold  season,  acquire 
and  maintain  the  winter  constitution.  (§  444,  p.  189.)    They 
have  more  radiation  of  heat  outwardly,  but  they  generate 
more  heat  inwardly  to  sustain  it.     But  those  who  are  always 
careful  to  cover   themselves   heavily,  retain   partially  their 
summer  constitution  through  the  winter.     Their  radiation  is 
then  increased,  but  their  internal  fire  does  not  burn  more 


« 

vigorously.  They  are  therefore  tender fl 
cannot  bear  what  others  do  without  suffering.  An  undue 
anxiety  to  guard  against  exposure,  manifested  in  excess  of 
clothing,  frequently  disarms  one  of  the  natural  protection 
against  the  effects  of  a  low  temperature.  Those  who  are 
over-careful  to  dress  warm,  and  never  walk  abroad  in  winter 
without  the  thickest  outer  garments  for  their  bodies,  over- 
shoes for  their  feet,  and  tippets  for  their  necks,  make  them- 
selves tender,  and  are  more  liable  to  be  affected  by  changes 
of  the  weather,  and  to  take  cold,  than  those  who  clothe 
themselves  more  judiciously,  and  develop  and  depend  more 
upon  their  own  internal  resources.  The  very  common  prac- 
tice of  schoolboys  wearing  woollen  tippets  about  their  necks 
has  caused  more  sore  throats  than  it  has  prevented. 

527.  Some  differ  very  widely  in  their  habits  of  dress  in 
various  periods  of  life.  I  know  of  men  who  once  were  ac- 
customed to  clothe  themselves  in  the  warmest  woollens  and 
furs,  and  who  never  went  into  the  open  air,  in  winter,  without 
extra  garments;  and  these  were  doubled  in  the  severest 
weather.  In  this  manner,  they  became  so  tender  as  to  suffer 
if  they  infringed  in  the  least  upon  their  law  of  habit.  But 
these  same  men,  by  slow  degrees,  have  left  off  their  extra 
dresses,  and  now  find  them  to  be  seldom  or  never  needed. 
They  were  before  so  delicate  that  they  felt  a  chill,  or  a  sore 
throat,  or  pain  in  the  muscles,  or  joints,  or  the  lungs,  if  they 
even  entered  the  street,  without  a  great  coat,  in  cold  weath- 
er. Now  they  walk  boldly  for  hours  without  extra  clothing, 
and  suffer  no  bad  or  uncomfortable  consequences.  Precisely 
the  reverse  sometimes  happens,  and  the  hardy  become  deli- 
cate from  an  opposite  change  of  habit. 


220  PHYSIOLOGY    AND   HEALTH. 


CHAPTER  X. 

Those  who  have  poor  or  insufficient  Food,  or  Dyspepsia,  or  breathe 
bad  Air,  need  more  Clothing.  —  More  Clothing  needed  in  dry  and 
windy  Weather  than  in  damp  and  still  Air.  —  More  needed  in 
travelling  than  when  quiet.  —  Every  one  should  be  clothed  com- 
fortably.  —  Hardening.  —  Old  People  and  Children  must  be  well 
clothed. 

528.  THE  quantity  of  clothing  depends,  not  only  upon 
habit,  but  upon  many  other  circumstances  which  are  con- 
nected with  the  health,  and  which  affect  the  generation  of 
internal  heat,  and  the  healthy  actions  of  the  skin.     If  one  is 
not  supplied  with  sufficient  fuel  for  the  internal  fire ;  if  he  is 
ill-fed,  and  has  insufficient  or  poor  food;  if  he  is  dyspeptic, 
and  his  stomach  is  unable  to  convert  his  food  into  the  chyle 
for  the  blood ;  if  nutrition  goes  on  heavily,  and  the  changes 
of  particles  are  slow ;    or  if  he  exercises  but  little,  and  the 
energies  of  his  life  are  dormant, — he  can  bear  less  expo- 
sure unprotected,  and  he  therefore  needs  more  clothing. 

529.  Or  if  the  lungs  are  supplied  with  insufficient  air;  if 
one  sits  in  a  crowded  and  unventilated  lecture  or  school  room 
for  hours ;  if  he  ascends  to  the  top  of  a  mountain,  where  the 
rarefied  atmosphere  contains  a  smaller  quantity  of  oxygen ; 
or  if  the  chest  is  encased  with  tight  dress,  so  that  it  cannot 
expand  and  receive  sufficient  air ;  or  if  the  lungs  are  diseased 
and'their  air-vessels  partially  closed;  if  in  any  way  the  blood 
receives  less  than  its  due  amount  of  oxygen,  —  then  there  is 
less  heat  to  be  given  out,  and  more  protection  is  required. 

530.  If  the  fuel  of  good  and  nutritious  food  is  not  sup- 
plied for  the  internal  fire,  there  must  be  greater  external 
fire,  or  more  protection ;  for  then  the  body  cannot  sustain  the 
loss  of  so  much  heat  as  would  pass  from  flesh  at  98°  to  a 
surrounding  atmosphere  at  the  ordinary  temperature  (65°  to 
70°)  of  comfortable  rooms.     Insufficiency  of  food  thus  cre- 
ates a  necessity  for  a  greater  expenditure  for  clothing  and 
warming. 


THE    SKIN.  221 

531.  It  is  manifest,  then,  that  there  can  be  no  positive 
and  universal  law  for  the  quantity  of  clothing.     This  must 
be    as   diverse  as  are  men's  habits,  health,  and  exposures. 
What  is  enough  for  one  man  may  be  too  much  for  another ; 
and  what  is  only  sufficient  for  comfort  and  for  security  from 
disorder  at  one  time,  or  in  one  assemblage  of  circumstances, 
may  be  oppressive  at  another  time,   and  in  other  circum- 
stances. 

532.  Dr.  Wilson  says,  "  I  have  endeavored  to  establish 
as  a  law  of  health  the  necessity  of  preserving  an  agreeable 
temperature  of  the  body"     "  I  should  wish  it  to  be  under- 
stood, also,  that  the  feelings,  if  the  nervous  system  be  sound, 
are  a   proper  channel  for  arriving  at  a  knowledge  of  the 
state  of  the  warmth  of  the  system."  *     It  may  be  said,  then, 
in   general   terms,    that   every   one   should--  wear   sufficient 
clothing  to  make  himself  comfortable,  and  to  secure  his  body 
from  disturbance  of  health.     More  than  sufficient  clothing 
prevents  the  free  radiation  of  heat,  and  causes  its  accumula- 
tion in  the  skin.     The  blood-vessels  of  the  surface  being 
stimulated  to  over-exertion,  the  perspiration  is  increased  from 
the  over-action  of  the  blood-vessels,  and  carries  off  the  sur- 
plus heat  by  evaporation.     If  a  person  wears  less  than  this, 
the  heat  is  carried  off  too  rapidly  by  radiation,  and  he  is 
chilled ;    the  perspiration  is  checked,  the  cutaneous  blood- 
vessels are  contracted,  the  balance  of  the  circulation  is  dis- 
turbed, and  internal  derangement  follows. 

533.  In  good  health,  a  sudden  and  momentary  chill  from 
exposure  to  cold  air,  or  a  cold  shower-bath,  is  not  followed 
by   these    unpleasant   consequences.      On  the  contrary,  re- 
action takes  place  in  the  cutaneous  blood-vessels,  and  a  glow 
of  heat  follows ;    and  one  is,  perhaps,  the  warmer    for  this 
sudden  transition.     But  continued  cold  is  injurious  both  to 
the  cutaneous  circulation  and  to  the  internal  health. 

534.  There  is  a  great  difference  in  the  power  of  bearing 
cold,  which  comes  from  the  habit  of  exposure.     The  driver 

*  On  the  Skin,  p.  108 

19* 


222  PHYSIOLOGY    AND    HEALTH. 

of  a  stage-coach  sits  on  his  elevated  and  unprotected  seat  in 
face  of  the  severest  winds  of  winter,  for  one  or  two  hours,  or 
even  more,  without  apparent  suffering,  while  his  passengers, 
less  hardy  than  himself,  and  perhaps  much  more  heavily 
clothed,  are  shivering  with  cold.  He  has  endured  this  ex- 
posure daily  through  the  entire  winter,  and  for  successive 
years,  and  has  become  hardened ;  but  they  have  been  accus- 
tomed to  the  mild  temperature  of  houses  and  shops,  or,  if 
they  lived  a  while  in  open  air,  they  kept  themselves  warm 
with  active  labor. 

535.  This  coachman  is  a  man  of  robust  constitution;  he 
eats  heartily  and  digests  easily,  and  is  well  nourished.  He 
attained  gradually  to  this  power  of  endurance,  and  now  he 
does  not  suffer.  The  pilot,  the  market-man,  &c.,  who  enjoy 
equally  good  original  health/  and  have  gone  through  a  simi- 
lar training,  may  bear  the  cold  as  well  as  he  does.  They 
too  are  hardened.  But  more  feeble  and  less  active  men 
cannot  thus  expose  themselves,  without  danger.  There  is  a 
common  but  erroneous  notion  that  any  one  can  harden  him- 
self by  exposure,  and  .become  able  to  endure  severe  cold 
without  much  outward  protection.  I  have  known  some 
sedentary  men,  whose  days  were  spent  in  warm  rooms 
or  shops,  attempt  to  harden  themselves  by  going  abroad  in 
the  winter  without  outward  garments ;  but  they  failed  to 
accomplish  their  purpose.  They  did  not  begin  with  slight 
trials,  and,  proceeding  gradually,  go  by  slow  degrees  from 
small,  to  greater  and  greater  exposures;  but  they  began 
with  the  greatest.  They  had  not  the  robust  health,  the 
hearty  appetite  and  vigorous  digestion,  nor  the  energy  of 
muscular  power,  that  belonged  to  laboring  men,  and  con- 
sequently they  did  not  generate  an  increase  of  internal  heat 
to  maintain  the  extraordinary  radiation.  Instead  of  return- 
ing from  their  cold  walks  or  rides  with  a  glow  upon  their 
cheeks,  and  the  flush  of  ruddy  health,  they  were  pale  and 
cold.  Instead  of  a  reaction  afterwards,  their  cutaneous  cir- 
culation continued  languid,  and  they  were  not  easily  warmed. 
They  became  more  susceptible  of  cold,  rather  than  more 


THE     SKIN.  223 

able  to  resist  it,  and  in  some  instances  their  health  failed, 
and  they  sank  under  the  experiment. 

536.  More   clothing  is  necessary  in   infancy  and  in  old 
age,  when  the  generation  of  internal  heat  is  more  feeble  than 
in  the  middle  periods  of  active  life.     It  is  a  mistake  to  sup- 
pose that  infants  should  be  lightly  clothed,  or  that  the  neces- 
sity of  warm  garments  for  them  is  the  mere  creation  of  habit. 
They  can  give  out  no  more  heat  than  is  prepared  within  ;  and 
as  this  is  less  in  them  than  in  others,  they  cannot  bear  an 
equal    loss  without   reducing   their   temperature  below  the 
natural  standard.     They  must   therefore  be  protected  with 
more  caution.     The  same  law  applies  to  the  aged,  and  even 
more  strictly,  inasmuch  as  their   sensations  are  so  blunted 
that  they  cannot  so  easily  tell  when  they  are  cold.      And 
oftentimes   they    are   suffering   serious    disturbance    before 
they  are  aware  of  it. 

537.  It  must  not  be  inferred,  from  the  preceding  sections, 
that  men  who  are  engaged  in  sedentary  employments,  or  who 
are  otherwise  than  robust,  cannot,  by  discreet  exposure,  ac- 
quire a  power  to  endure  the  weather  of  cold  seasons.     Pre- 
cisely the  reverse  is  the  fact.     But  this  exposure  must  be 
just  in  proportion  to  the  power  of  the  body  to  bear  it,  and 
increased  only  as  fast  as  the   energies  of  the    constitution 
increase.     It  should  always  be  accompanied  with  so  much 
clothing  that  the  body  shall  not  suffer  while  abroad,  and  the 
chill  must  not  be  so  great  that  reaction  will  not  take  place 
immediately  after  returning  to  the  house.     With  these  pre- 
cautions of  suiting  the  exposure  to  the  powers  of  the  consti- 
tution, wearing  clothing  sufficient  for  comfort,  or  exercising 
actively  enough  to  sustain  the  increased  demands  for  heat, 
even  the  feeble  can  generally  acquire  a   power   to   endure 
all  the  weather  of  this  climate. 


224  PHYSIOLOGY    AND   HEALTH. 


CHAPTER  XI. 

Clothing  should  be  of  loose  Texture,  and  fit  loosely  to  the  Body.  — 
Various  Materials  of  Clothing.  —  Linen,  Cotton,  Silk  Wool. — 
Flannel,  next  to  the  Skin. 

538.  THE  great  object  of  clothing  being  to  defend  the 
body  from  cold,  by  preventing  the  radiation  of  heat,  the  ma- 
terials should  therefore  be  bad  conductors  of  heat.      This 
non-conducting  principle  is  not  so   much   in  the  material 
itself  as  in  the  air  which  is  retained  within  its  loose  textures. 
"  In  every  case  it  is  the  power  which  the  coverings  possess 
o£  detaining  atmospheric   air  in  their  meshes  which  is  the 
cause  of  this  warmth."  *     Clothes  of  loose  and  open  texture 
contain  more  air  than  those  which  are  close  and  firm,  and 
garments  that  are  lined  and  wadded  with  very  light  material 
offer  the  same  advantage  of  holding  layers  of  air  within  the 
spaces  of  their  texture.     The  loose  and  light  kinds  of  wad- 
ding are  the  warmest,  because  they  afford  the  largest  space 
for  air.     The  old-fashioned  bed-quilts,  which  were  made  of 
double  layers  of  old  and  worn  woollen  cloth,  and   a  small 
layer  of  wool,  very  closely  quilted,  were  much  cooler  cover- 
ings than  the  modern  quilts  of  cotton  cloth,  with  very  light 
wadding  of  cotton   or  eider  down.     For  the  same  reason, 
threadbare  garments  are  colder   than  new,  from  which  the 
nap  is  not  worn  off;    and    those   which  have  a  long  and 
shaggy  nap    are  much  warmer  than  those  which  are  well 
sheared  and  nicely  dressed. 

539.  On   the   same  principle,   the   garments   should    be 
made  to  fit  loosely  to  the  body,  so  as  to  leave  a  space  for  the 
air  between  them  and  the  flesh.     "  Every  one  is  practically 
aware  that  a  loose  dress  is  much  warmer  than  one  which 
fits  closely ;  that  a  loose  glove  is  warmer  than  a  tight  one ; 
and  that  a  loose  boot  or  shoe  is  more  comfortable  in  the 
winter  than  a  tight  one."  *     The  loose  sack  is  a  warmer 
outer  garment  than  the  close-buttoned  surtout.     If  there  are 

*  Wilson  on  the  Skin. 


THE  SKIN.  225 

several  layers  of  dresses,  each  one  should  be  considerably 
looser  than  the  next  one  within,  so  that  a  layer  of  air  may 
be  kept  between  them.  In  all  these  cases,  the  several  strata 
of  air  between  the  different  garments,  and  in  the  meshes  of 
the  loose  textures  of  cloth,  acting  as  non-conductors,  prevent 
the  passage  of  heat.  From  this  cause,  the  attic  chamber, 
which  has  nothing  but  the  roof  between  it  and  the  burning 
sun  or  freezing  air,  is  much  hotter  in  the  summer  and  colder 
in  the  winter  than  the  chamber  below,  which  has  the  air 
of  the  attic  between  it  and  the  solar  rays  or  the  outer 
atmosphere. 

540.  The   various    materials   of   our    garments  —  linen, 
cotton,  silk,  and  woollen  —  have  different  qualities,  and  are 
consequently  suitable  for  different  persons  and  seasons.     The 
fibre  of  linen  is  round,  pliable,  smooth,  ancf  soft  to  the  skin ; 
it  therefore  makes  a  most  agreeable  garment.     Yet  it  is  a 
good  conductor,  and  allows  the  heat  to  pass  off  rapidly,  and 
therefore  feels  cold  when  it  touches  the  skin.     Moreover  its 
fibre  is  porous,  and  absorbs  and  retains  the  water  of  perspira- 
tion.    Water  being  a  still  better  conductor  than  linen,  those 
who  wear  this  cloth  are  chilled  after  sweating,  even  in  a  hot 
day.     For  this  reason,  linen  is  more  and  more  abandoned  as 
an  article  for  under-wear  in  hot  climates. 

541.  Cotton  is  a  worse  conductor,  and  therefore  warmer 
than  linen.     It  is  also  soft,  though  less  so  than  linen,  and 
less  pleasant  to  the  touch,  for  its  fibres  are  not  rounded,  but 
"  are  flat  and  have  sharp  edges,"  which  irritate  some  delicate 
skins.     But  it  does  not  absorb  moisture,  and  for  this  reason 
it  is  the  favorite  and  proper  under-dress  of  all  climates. 

542.  Silk  is  not  so  good  a  conductor,  and  is  warmer  than 
cotton.     Its  fibres   are  round  and  pliable,  and  it  makes  a 
pleasant  garment  for  the  skin.     It  attracts  no  moisture,  and 
gives  a  sensation  £>f  freshness  to  the  surface  when  it  touches 
it.     But,  "  on  the  slightest  friction,  it  disturbs  the  electricity, 
and  then  becomes  a  source  of  irritation,"  and  in  very  delicate 
and  irritable  constitutions  it  sometimes  produces  eruptions. 

543.  Wool  is  the  worst  conductor  of  heat,  and  is  there- 


226  PHYSIOLOGY  AND  HEALTH. 

fore  the  warmest  for  winter  garments.  It  absorbs  no  moist- 
ure, and  defends  the  wearer  from  the  chills  that  frequently 
succeed  perspiration  in  a  hot  but  changeable  climate.  Its 
fibre  is  porous,  and  contains  minute  portions  of  air,  and  it 
makes  cloth  of  loose  texture.  But  its  fibre  is  rough  and 
scaly,  and  is  very  irritating  to  delicate  skins.  It  also  disturbs 
the  electricity  even  more  than  silk.  For  these  reasons, 
many  cannot  bear  any  woollen  garment  next  to  their  bodies. 
However  fine  and  delicate  the  fabric,  it  always  irritates  them. 
544.  It  is  desirable  to  guard  the  warmth  of  the  skin,  not 
only  from  the  permanent  influence  of  the  atmosphere,  but 
against  any  sudden  changes  which  would  produce  a  chill. 
If  our  clothing  is  filled  with  water,  the  heat  is  carried  off 
very  rapidly,  as  water  is  a  good  conductor.  Wool  is  there- 
fore a  more  appropriate  material  to  be  worn  next  to  the  skin 
than  linen ;  and  if  the  garment  is  made  loose,  and  of  fine 
texture,  such  as  thin  flannel,  it  is  a  great  safeguard  against 
the  effects  of  changes  in  hot  climates  and  hot  seasons ;  and 
the  feeble  and  delicate  would  be  safe  to  wear  it  at  all  times. 


CHAPTER   XII. 

Advantage  of  Flannel  in  hot  Climates.  —  Cutaneous  Excretions  re- 
ceived on  the  Clothing.  —  Foul  Clothing  offensive  to  the  Sense  of 
Touch  —  Clothing  and  Beds  should  be  aired. 

545.  DR.  ANDREW  COMBE  quotes  the  example  of  a  Brit- 
ish ship  of  war,  which,  after  sailing  for  two  years  among  the 
icebergs  on  the  coast  of  Labrador,  was  immediately  ordered 
to  the  West  India  station.  On  this  change  of  location,  every 
man  was  provided  with  flannel  shirts  and  drawers,  which 
they  wore  while  in  the  hot  climate.  "  The  ship  proceeded 
to  the  station  with  one  hundred  and  fifty  men,  visited  almost 
every  island  in  the  West  Indies  and  many  of  the  ports  in  the 
Gulf  of  Mexico,  and,  notwithstanding  the  sudden  transition 
from  extreme  climates,  returned  to  England  without  the  loss 


THE    SKIN.  227 

of  a  single  man,  or  having  any  sick  on  board."  The  same 
commander  had,  at  another  time,  the  charge  of  the  gun-brig 
Recruit,  which  lay  about  nine  weeks  at  Vera  Cruz,  and  used 
the  same  precautions  in  the  clothing  of  his  crew,  and  thus 
preserved  the  health  of  his  men,  while  the  other  ships  of  war, 
which  were  anchored  in  the  same  harbor,  and  exposed  to  the 
same  influence  of  climate  and  labor,  lost  two  fifths  of  their 
men.* 

546.  It  should  be  stated,  that  this  wearing  of  flannel  was 
not  the  only  precaution  taken  by  this  provident  officer  for  the 
health  of  his  crew.     Every  kind  of  pains  was  taker*  to  secure 
a  dry  and  pure  atmosphere  in  the  seamen's  sleeping  apart- 
ments; and  every  means  of  cleanliness  used,  so  that   they 
should  neither  breathe  foul  air  nor  be  exposed  to  foul  exhala- 
tions from  the  walls  and  floors  of  their  roonas. 

547.  A  commander  of  a  merchantman,  who  had  sailed 
much  to  St.  Petersburg,  in  Russia,  and  to  the  West  Indies, 
East  Indies,  and  Brazil,  from  Boston,  informed  me  that  he 
provided  flannels  as  carefully  for   his   southern    as  for   his 
northern  voyages,  and  he  found  them  as  effectual  a  safeguard 
against  the  diseases  of  the  warm  climates   as    against  the 
chills,  colds,  catarrhs,  and  rheumatisms  of  the  north. 

548.  Those  who  practise  the  cold  water  system  in  the 
treatment  of  disease,  and  who  seem  to  bear  exposure  to  cold 
water  and  cold  air  with  remarkable  ease,  discard  flannels  as 
injurious.     But  their  experiment  has  not  been    sufficiently 
tried  to  establish  a  universal  law.     It  is  therefore  safe,  at 
least  for  the  old  and  the  delicate,  to  adhere  to  their  custom 
of  wearing  flannels  next  to  the  skin. 

O 

549.  The  cutaneous  excretions  are  first  received   upon 
the  clothing,  and  then  a  part  of  them  are  carried  away  by 
the   atmosphere,  and  a  part  of  them  are  retained  upon  the 
garments.     It  is  easy  to  perceive  this,  by  seeing  the  dark 
and  dingy  color  of  the  white  cotton  or  linen  which  has  been 
worn  next  to  the  skin,  and  so  closely  covered  by  the  outer 
clothing,. that  no  dust  nor  dirt  could  come  to  it  from  abroad. 

*  Combe's  Physiology,  Chap.  III. 


228  PHYSIOLOGY    AND    HEALTH. 

This  coloring  matter  upon  these  under-dresses  could  only 
come  from  the  skin.  If  further  proof  were  needed,  notice 
the  foul  odor,  on  Saturday,  of  the  inner  garments  of  some 
laborious  men,  who  do  not  bathe,  and  who  change  their 
shirts  but  once  a  week. 

550.  Clothing   that  is  soiled  by  being  worn  next  to  the 
flesh  is  offensive  to  the  touch  as  well  as  the  sight  and  the 
smell.     Shakspeare   makes   the   merry   wives   of   Windsor, 
when  they  wished  to  throw  the  greatest  indignity  on  Sir  John 
FalstafF,  put  him  into  a  basket  of  foul  linen,  which  was  cov- 
ered with  the  cutaneous  excretions  of  the  body.     We  feel  a 
sensation  of  comfort  when  we  put  on  clean  linen,  and  of  dis- 
satisfaction when  we  put  on  that  which  is  otherwise.     And 
without  the  aid  of  the  eye  or  nostrils,  the  sensitive  skin  can 
determine  whether  a  garment  is  pure  or  foul,  when  we  put  it 
on.     And,  however  dark  it  may  be,  we  can  tell  by  the  feeling 
whether  our  sheets  are  fresh  and  clean,  or  soiled  arid  worn. 
No  children  are  more  particular  to  put  off  foul  clothing  and 
put  on  clean,  than  the  blind  at  the  Institution  at  South  Boston. 

551.  To  prevent  this -accumulation  of  the  cutaneous  ex- 
cretions, which,  being  retained,  become  foul  and  offensive, 
the  garments  which  come  in  contact  with  the  body  should 
be  frequently  changed  and  washed.     None  of  the  clothing 
of  the  day  should  ever  be  worn  in  the  night,  nor  ought  the 
clothing  of  the  night  to  be  worn  in  the  day.     Morning  and 
evening  there  should  be  a  complete  change  of  every  article 
of  dress;    and  each   garment,  when   taken    off,  should   be 
separately  spread,  in  order  that  the  air  may  come  in  contact 
with  all  their  surface.     By  this  airing,  much  of  the  foul  ex- 
cretions is  carried  away  from  them.     The  clothing  which  is 
taken  off  at  any  time  to  be  reworn  should  not  be  hung  up 
in  a  close  closet,  nor  packed  in  drawers  or  trunks,  until  it 
shall  have  been  thoroughly  aired  by  a  similar  exposure. 

552.  That   thrifty  housewifery  which   requires   the  beds 
to  be  made  up  in  the  morning  as  soon  as  vacated  by  the 
lodgers,  is   prejudicial  to   health.     The   beds    and    bedding 
need  airing  more  than  the  day  clothing.     This  last  is  ex- 


THE    SKIN.  229 

posed  to  some  changes  of  air  most  of  the  time  while  it  is 
worn,  and  a  portion,  at  least,  of  the  excretions  is  dissipated. 
But  as  the  body,  while  sleeping,  continues  in  one  place,  and 
with  no  change  of  air  through  the  night,  the  bed-clothing 
loses  none  of  the  animal  excretions,  and  there  they  remain 
in  the  morning.  The  bed,  therefore,  should  be  opened,  its 
several  parts  separated,  and  the  mattress,  the  feather-bed,  and 
the  under-bed,  should  be  laid  apart  one  from  another,  and 
the  sheets,  blankets,  and  all  the  other  bedding  hung  on  chairs 
or  other  things  which  will  allow  the  air  to  reach  both  their 
surfaces.  And  thus  should  the  chamber  be  left,  and  the  bed 
be  aired  for  some  hours  each  day,  with  a  window  open,  how- 
ever cold  the  air. 

553.  It  is  an  uncomfortable  as  well  as  an  unhealthful  cus- 
tom  to  use  the  single  cabin  of  canal  boats  for  day  as  well 
as  for  night  room.     There  all  the  work  of  life  is  carried  on. 
There  the  passengers  sit  and  eat  during  the  day,  and  sleep 
during  the  night.     To  prepare  for  lodging,  the  beds  are  fixed 
to  the  walls  by  means  of  hooks  and  ropes,  every  evening; 
and,  in  the  morning,  in  order  to  make  room  for  the  break- 
fast table,  these  beds  are  all  taken  down  and  packed  in  aa 
small  a  compass  as  possible ;  without  opportunity  of  airing, 
or  any  means  of  purification,  they  are  closely  compressed 
through  the  day,  until  they  are  needed  again  at  night.     In 
addition  to  the  unavoidable  excretions  of  the  present  night, 
these    beds   retain    the    accumulated    excretions    of  several 
nights,    and   perhaps   of    successive    passengers    during    a 
whole  trip. 

554.  Some  dwellings  of  the  poor  in    cities  present  the 
same  seeming  necessity  of  piling  the  beds  and  the  night 
clothes  into  one  close  heap,  to  allow  room  for  the  day  opera- 
tions of  the  family.     Press-beds    and    sofa-beds    in   sitting- 
rooms,  which  are  shut  up  immediately  after  being  left  in  the 
morning,  are  liable  to  the  same  objection.     They  have  no 
opportunity  of  being  aired,  and  the  foul  excretions  of  the 
night  are  retained  during  the  day,  to  irritate  the  skin  of  the 
lodger  when  he  returns. 

20 


230  PHYSIOLOGY   AND    HEALTH. 


CHAPTER  XIII. 

Dead  Particles  of  Cuticle  are  lodged  on  the  Skin.  —  We  bathe  the 
Hands  and  Face,  but  the  Body  is  not  generally  bathed.  —  Those  who 
bathe  daily  have  soft  Skin.  —  Bathing  a  religious  Rite  in  ancient 
Times  and  in  Oriental  Countries.  —  Much  practised  in  Russia  and 
Finland. 

555.  THE  cuticle  is  constantly  casting  off  its  outer  layers 
in  scurf  or  minute  scales.     Some  animals  cast  their  skins 
entire,  and  others  cast  their  shells  once  a  year ;  but  man  is 
incessantly  casting  his  skin.     The  outer  scales,  which  are 
the  dead  particles  of  the  cuticle,  lie  loosely  on  the  surface, 
and  can  be  scraped  off  with  a  knife  at  any  time ; '  they  have 
then  the  appearance  of  branny  powder.     Some  animals  cast 
their  hair  or  shed  their  coats,  and  birds  moult  their  feathers 
annually.     But  the   hair  and  nails  of  man  grow  from  their 
roots,  and  thrust  out  their  outer  extremities,  which,  if  not 
trimmed,  would  be  continually  breaking  and  dropping  off. 

556.  If  any  one  who  had  for  a  long  time  deprived  him- 
self of  the  needful  luxury  of  a  warm  bath  should  remain  for 
several  minutes  in  one,  he  would  be  surprised  to  see  how 
large  a  quantity  of  this  accumulated  matter  of  the  dead  skin 
he  could  rub  off  with  his  hands  or  a  flesh-brush.     The  re- 
moval of  this  gives  to  the  skin  a  very  agreeable  sensation  of 
comfort.      This  is  more  perceptible    after  taking   a   warm 
than  a,  cold  bath. 

557.  We  bathe  the  face  and  hands  daily,  and  oftener,  and 
know  how  comfortable  the  skin  upon  those  parts  feels  after 
this  operation.     But  if  this  duty  is  neglected,  the  skin  is 
irritable  and  irritated ;  it  seems  stiff  and  loaded,  and  we  feel 
disposed  to  scratch  and  rub  it  fo  remove  the  disagreeable 
burden.     But  the  other  parts,  which  are  not  so  frequently 
washed,  are  not  so  easily  offended.     They  bear  the  burden 
of  accumulated    excretions  and   dust  with   Jess    complaint. 
But,   if  they  were  cleansed  as  faithfully  as  the  hands  and 
the  face,  they  would  be  equally  sensitive,  and  feel  as  keenly 


TUB     SKIN.  231 

the  comfort  of  a  bath  and  the  discomfort  of  neglect.  This 
sensibility  of  the  skin  of  the  hands  and  face  is  a  mere  mat- 
ter of  cultivation,  and  might  as  well  be  cultivated  in  the 
skin  of  the  other  parts  which  are  covered  with  clothing. 
But  those  parts  which  are  not  exposed  to  sight  are  with 
most  people  rarely,  and  with  some  never,  bathed;  and  the 
great  majority  of  mankind  leave  so  much  of  their  surface 
unwashed  and  untouched  with  water,  from  summer,  through 
the  entire  cold  season,  until  summer  again  returns. 

558.  The  consequence  of  this  negligence  of  ablution  is, 
that  the  skin  becomes  overloaded  with  the  gathered  excre- 
tions of  months  and  years ;  it  loses  its  exquisite  sensibility  ; 
it  is  less  able  to  throw  off  the  waste  of  the  body ;  the  cu- 
taneous   circulation  is  not  so  well   sustained;  the   skin    is 
less  supple  and  elastic,  and  less  able  to  nfaintain  the  equi- 
librium of  heat;  and  the  whole  body  is  comparatively  dull 
and  inactive.     In  those  who  are  accustomed  to  take  their 
daily  entire  bath,  the    whole  skin  is  soft  and  elastic ;    the 
cutaneous  waste  is  carried    freely  away.     They  are  conse- 
quently enabled  to  bear  the  heat  and  cold,  over  their  whole 
frani3,  with  much  more  ease  than  others  do  who  wash  their 
hands  and  face  alone;  and  they  enjoy  a  more  acute  sensi- 
bility of  skin,   a   general  lightness    and    buoyancy  through 
their  frame. 

559.  To   maintain   the   most  perfect   health    of  the   skin 
and  of  the  internal  organs,  the  whole  surface  should  be  daily 
cleansed  of  all  its  excretions,  —  the  oil,  the  scales  of  the  cu- 
ticle, and  the  salts  of  the  perspiration,  —  and  also  of  the  other 
matters  which  lodge  on  the  body  and  become  mixed  with 
these.     No  part  should  be  neglected.     Water  will  remove  the 
salts,  and  soap  the  oily  excretions.     Nothing  can  be  substi- 
tuted for  soap.     Some  have  attempted  to  use  wash-powder, 
and  others  sometimes  use  alcohol  or  spirits ;    but  none  of 
these  combine  with  the  oily  matter,  or  dissolve  the  others, 
and  cleanse  the  skin.     "  Soap,"  says  Dr.  Wilson,  "  renders 
the  cutaneous  product  of  the  skin  freely  miscible  with  water 
and  hence  it  is  an  invaluable  agent  in  purifying  the  skin.     1 


PHYSIOLOGY    AND    HEALTH. 

may  affirm  that  it  is  an  indispensable  aid  ;  for  in  no  other  way 
can  the  cutaneous  substance,  and  the  dirt  which  adheres  to  it, 
be  thoroughly  removed  from  the  surface."  *  No  other  matter 
applied  to  the  surface  will  give  it  the  healthy  glow,  the  com- 
fortable sensation,  and  the  natural  and  lively  look,  and  beau- 
tiful hue,  that  are  left  by  soap  and  water.  Various  kinds  of 
powders  are  sometimes  used  upon  the  face,  with  the  mistaken 
notion  of  improving  its  beauty.  These  mix  with  the  oily 
excretions,  and  form  a  pasty  compound.  They  increase  the 
burden  upon  the  skin,  and  impair  its  vitality,  deaden  its 
liveliness  of  expression,  and  sully  the  brightness  of  its  color. 

560.  Some  nations  have  practised  bathing  as  a  religious 
rite.     It  was  a  good  custom  of  the  ancient  Israelites,  the 
Egyptians,  and  the  inhabitants  of  the  East  Indies,  to  bathe 
as  a  part  of  duty,  as  typical  of  moral  purification.      The 
Greeks  and  Romans  considered   bathing  so  essential,  that 
their  public  bathing  establishments  were  large  and  magnifi- 
cent, and  their  private  baths  were  as  splendid  as  the  means 
of  the  owners  would  permit. 

561.  The  moderns  have  not  improved  upon  the  ancients 
in  the.  care  of  their  skins;  nor  have  the  civilized  nations  of 
Central  and  Western  Europe,  and  America,  improved  upon 
the   less  cultivated    Hindoos,    Persians,    and    Turks.     The 
Russians    and  the  Finlanders  indulge  themselves  very  much 
in  this  matter,  and  baths  are  attached  to  houses  of  all  classes 
in  Finland,  Lapland,  Sweden,  and  Norway. t     But  the  Eng- 
lish and  the  Americans  do  not  generally  use  the  bath. 

562.  There  are  various  kinds  of  baths,  —  the  cold  and  the 
warm,  the  shower  and  the  vapor  bath,  —  all  of  which  have 
their  appropriate  uses.     The  Russians  are  very  fond  of  their 
peculiar  vapor    bath.     This  is  one   great   hall,  warmed  by 
stoves ;  large  red-hot  "stones  are  placed  on  the  stone  floor, 
and  water  poured  upon  them ;  the  room  is  then  filled  with 
vapor  heated  up  to  120°  or  130°  Fahrenheit.     Dr.  Grenville 
says  he  found   that  the  Finlanders,  in  some  instances,  sat 
half  an  hour  in  vapor  baths  heated  by  hot  stones  to  169° 

*  On  the  Skin.  f  Bell  on  Baths.  D.  33. 


THE    SKIN.  233 

The  bathers,  covered  with  the  steam,  sit  on  benches  until 
they  break  out  with  a  profuse  sweat.  Then  they  are  washed 
with  soap  suds,  and  next  buckets  full  of  warm  water,  and 
lastly  of  cold  water,  are  poured  upon  the  head.  Sometimes 
the  Russians  will  run  from  this  steam  bath  and  plunge  into 
a  bank  of  snow,  and  feel  no  injury;  on  the  contrary,  a. com- 
fortable glow  of  heat  comes  from  the  vigorous  circulation, 
which  the  cold  of  the  snow  stimulates.* 


CHAPTER   XIV. 

Cold   Bathing.  —  Sponge   Bath.  —  The  most  Laborious  need   Daily 
Bath.  —  Some  cannot  bear  Cold  Bath. 

563.  IF  the  health  is  good,  and  the  body^is  full  of  animal 
heat,  the  cold  bath  answers  the  purpose  of  health  in  summer ; 
and  if  used  with  energy  and  perseverance,  it  is  also  sufficient 
for  winter.     It  is  an  excellent  habit  of  some  to  take  a  cold 
bath  every  morning,  both  winter  and  summer,  not  omitting 
it  even  in  the  coldest  weather.     Those  who  do  this  find  it 
not   only  very  endurable,  but   they  usually   enjoy    a   glow 
throughout  all  the  surface  afterwards.     So  far  from  suffering 
from  cold,  the  reaction  of  the  cutaneous  circulation  produces 
an  increase  of  heat,  and  they  are  made  the  warmer  by  this 
ablution. 

564.  It  is  desirable  that  every  one  should  be  able  to  take, 
daily,  a  plunge  bath.     But  this  is  impossible  for  all.     The 
convenience  of  a  large  bathing  tub  cannot  be  provided  in 
every   house.      Yet   a   good  substitute  is  within  the  reach 
of  all.     The  sponge  bath  is  very  easily  taken,  and  requires 
but  a  very  limited  and  simple  apparatus.     Provide  a  large 
wash-bowl  and  a  piece  of  extra  carpet,  which  should  receive 
the  drops  that  fall  to  the  floor,  —  or,  what  is  much  better,  a 
large  tin  basin  in  shape  of  a  hat,  with  a  shallow  crown  and 
very  broad  brim,  —  and  then  a  soft  towel  for  wiping,  and  a 
crash  towel  for  friction.     These  are  all  that  are  needed,  and 

*  Bell,  Chap.  II. 

20* 


234 


PHYSIOLOGY    AND    HEALTH. 


with  these,  this  very  grateful  and  invigorating  ablution  can 
always  be  performed  on  getting  out  of  the  bed. 

565.  The  cold  bath  is  most  conveniently  taken  as  soon 
as  one  gets  out  of  his  bed.     It  is  best  to  take  it  when  one  is 
warm,  when  there  is  sufficiency  of  heat  to  bear  the  shock 
and  to  produce  the  reaction.     This  bath  should  not  be  so 
long  continued  in  winter  as  materially  to  reduce  the  heat 
and  energies  of  the  circulation  in  the  skin;  and  immediately 
after  it  the  surface  should  be  dried  and  rubbed  until  the  re- 
action commences.     The  exercise  necessary  for  this  rubbing, 
which  the  bather  should  do  for  himself,  and  the  friction  on 
the  surface,  excite  the  circulation,  and  produce  a  very  pleas- 
ant glow  of  warmth  upon  the  whole  frame. 

566.  None  need  this  bath  more  than  the  most  industri- 
ous laborers,  who  have  the  greatest  demand  for  their  strength, 
and  therefore  need  to  take  the  greatest  pains  to  develop  it. 
Yet  it  is  generally  urged  by  them,  as  a  reason  for  the  neg- 
lect of  this  duty,  that  their  avocations  allow  them  no  time 
for  this,  and,  however  well  it  may  do  for  the  wealthy  and  the 
men  of  leisure,  it  cannot  be  performed  by  the  poor  and  labo- 
rious, who  are  always  in  haste  in  the  morning  to  go  to  their 
work.     This  is  certainly  a  mistake  of  calculation.     The  me- 
chanic considers  no  time  lost  that  he  devotes  to  putting  his 
machine  in  good  order ;  and  the  wagoner  thinks  it  an  advan- 
tageous disposition  of  his  time  to  rub  and  curry  his  horses 
faithfully.     Both  of  these  believe  that  they  will  be  enabled  to 
accomplish  so  much  the  more  for  this  preparatory  care.     So 
it  is  with  the  laborer's  body.     In  order  that  it  should  be  able 
to  accomplish  the  most  work,  it  must  be  put  in  the  best 
working  order  ;  and  this  is  done,  in  part,  by  cleansing  the 
skin  of  all  impurities,  unloading  it  of  its  burdens,  and  so  pre- 
paring it  for  its  functions  that  its  work  will  not  only  go  on 
well  during  the  day,  but  contribute  its  portion  to  the  general 
health  and  the  muscular  power. 

567.  This  cold  bathing  is  a  general  rule,  but  not  a  uni- 
versal one  for  mankind ;  for  some  cannot  take  it  with  safety. 
If  the  body  is  in  full  health,  and  the  circulation  vigorous, — 


THE    SKIN.  235 

if,  after  the  bath,  there  is  reaction  and  a  glow  of  heat  through- 
out the  surface,  —  then  the  cold  bath  is  both  safe  and  useful ;. 
but  if  the  body  is  feeble,  or  the  flesh  cold,  and  not  easily 
warmed  after  the  bath,  or  even  if  the  heat  does  not  naturally 
and  spontaneously  return,  then  this  bath  is  injurious,  and  a 
tepid  bath  should  be  substituted  in  its  stead.  Any  one  can 
tell,  by  his  own  experiment,  what  temperature  he  can  best 
enjoy,  and  how  great  a  degree  of  cold  will  be  followed  by 
the  comfortable  sensation  of  warmth  in  his  skin. 

568.  Even  for  those  who  take  the  daily  cold  bath,  the 
warm  bath  is  occasionally  necessary.  This  is  a  more  ef- 
fectual cleanser  of  the  surface.  It  softens  and  allows  the 
removal  of  the  dead  scurf  of  the  skin  more  readily  than  the 
others ;  and  for  those  who  do  not  practise  the  daily  ablution, 
the  occasional  use  of  the  warm  bath,  for  rftere  cleanliness  as 
well  as  for  health's  sake,  should  not  be  omitted. 


CHAPTER    XV. 

Effect  of  Cold  Bathing.  —  Protects  against  Cold.  —  Feeble  and  con- 
sumptive Persons  should  bathe.  —  Time  for  Bathing.  —  Conditions 
of  Bathing. 

569  THE  effect  of  the  cold  bath  is  not  only  to  invigorate 
the  body,  and  give  a  tone  and  activity  to  both  the  skin  and 
to  the  internal  organs,  but  it  fortifies  the  skin,  so  that  it  ia 
better  able  to  endure  the  exposures  to  the  cold  abroad,  I 
formerly  clothed  myself  very  carefully,  seldom  went  abroad 
without  an  overcoat  in  the  winter,  and  often  wore  a  cloak  over 
this.  Seven  years  ago,  I  began  the  practice  of  cold  bathing, 
and  have  followed  it  without  intermission  since,  breaking  the 
ice  in  the  coldest  weather,  and  bathing  in  my  chamber, 
where  was  no  fire.  I  now  wear  lighter  clothing  in  winter, 
a  great  coat  much  less  than  formerly,  and  never  an  extra 
cloak;  and,  with  so  much  less  protection,  I  suffer  less  from 
cold  than  when  I  was  clothed  more,  but  did  not  bathe. 


236  PHYSIOLOGY    AND    HEALTH. 

570.  Dr.  Andrew  Combe  confirms  this  effect  of  the  daily 
cold  bath  by  his  own  personal  experience,  and  by  the  ob- 
servation of  others.     "  Instead  of  being  dangerous,  it  is, 
when  well  managed,  so  much  the  reverse,  that  the  author  of 
these  pages  has  used  it  much,  and  successfully,  for  the  ex- 
press purpose  of  diminishing  this  liability,  both  in  himself 
and  in  others,  in  whom  the  chest  is  delicate.     In  his  own 
instance,  in  particular,  he  is  conscious  of  having  derived 
much    advantage   from    its   regular   employment,   especially 
in  the  colder  months  of  the  year,  during  which  he  has  uni- 
formly found  himself  most  effectually  strengthened  against 
the  impression   of  cold,  by  repeating   the  bath   at  shorter 
intervals  than  usual.     Few  of  those  who  have  steadiness  to 
keep  up  the  action  of  the  skin  by  the  above  means,  and  to 
avoid  strong  exciting  causes,  will    ever  suffer  from  colds, 
sore  throats,  or  similar  complaints."  * 

571.  For  the  weakly, — for  those  who  are  liable  to  pul- 
monary complaints,  who  may  have  any  hereditary  disposition 
to  consumption,  or  who  are  subject  to  rheumatism,  —  the  cold 
bath,  or,  if  this  cannot  "be  borne,  the  warm  or  tepid  bath,  is 
one  of  the  means  of  protection,  and  should  never  be  omitted 
by  people  of  such  tendencies.     It  should  be  begun  in  sum- 
mer, and  practised,  without  intermission,  through  the  autumn 
and  winter ;  and  the  gradual   increase  of  strength   and  the 
power  of  endurance  will  keep  pace  with  the  gradual  approach 
of  the  cold  season. 

572.  It  has  before  been  stated  (§  565,  p.  234)  that  one 
should  take  his  bath  in  the  morning,  on  rising  from  the  bed. 
This  is  a  matter  of  convenience;  for  then  the  labor  of  un- 
dressing is  spared,  and  the  means  may  be  ready.      This, 
however,  is  not  to  be  unfversally  practised.     To  some,  —  the 
feeble  and  the  debilitated,  and  to  others  of  peculiar  tempera- 
ment,—  the  bath  upon  an  empty  stomach,  when   the  systerti 
wants  nourishment  from    the   fast  of  ten   or  twelve  hours, 
would  be  injurious.     On  the  other  hand,  the  bath  is  not  the 
safest  and  best,   when   taken  upon   a  full  stomach,  imme- 

*  Physiology,  Chap.  III. 


THE    SKIN.  237 

diately  after  meals.  For  then  the  cold  bath  might  drive  the 
blood  too  much  within,  and  oppress  the  stomach,  which  is 
already  excited  with  the  work  of  digestion ;  and  the  warm 
bath,  by  relaxing  the  cutaneous  vessels,  might  draw  too  much 
of  the  blood  outward,  when  it  is  needed  for  the  work  within. 
In  either  case,  the  balance  of  the  circulation  is  disturbed, 
and  the  digestion  is  interrupted. 

573.  The  best  time  for  the  bath  is  in  the  forenoon,  after- 
noon, or  evening,  when  the  system  is  well  nourished,  and 
the  stomach  is  not  full,  nor  the  duodenum  empty;   never- 
theless, the  vigorous  and  robust  may  take  it  in  the  morning, 
before  eating,  with  impunity,  and  even  with  advantage. 

574.  There  is  a  very  common  notion  that  it  is  injurious 
to  go  into  the  water  when  the  body  is  warm.     We  have  seen 
(§  562,  p.  233)  that  the  Russians  go  from  the  hot  vapor  bath,  in 
a  profuse  perspiration,  into  the  snow.    It  must  not  be  supposed 
that  the  case  of  one  of  these,  heated  by  the  vapor  bath,  is 
strictly  analogous  to  that  of  one  who  is  profusely  perspiring 
with  running  or  other  exercise ;  and  therefore  the  practice 
which  is  safe  for  the  Russians  in  one  case,  may  be  unsafe 
for  one  who  is  differently  heated.     Yet  the  contrary  is  not 
true.     The  rule  which  is  often  enjoined  upon  boys  and  men, 
that,  when  they  go  to  the  river-side  or  sea-shore  to  bathe, 
they  should  first  sit  on  the  bank,  in  the  cool  air,  until  their 
temperature  is  reduced  somewhat  toward  that  of  the  water, 
lest  they  be  injured  by  the  sudden  change,  is  not  a  good 
one.    One  should  not  go  into  a  cold  bath  when  he  is  already 
cold  —  when  he  has  lost  so  much  heat  that  he  can  spare  no 
more,  for  any  further  reduction  would  be  injurious. 

575.  The  practice  of  two  young  men,  who,  several  years 
since,  bathed  in  the  Connecticut   River   daily,  during  the 
summer  and  autumn,  even  through  the  month  of  November, 
was  contrary  to  this ;  and  it  certainly  was  successful  in  their 
case,  and  doubtless  may  be  in  others  similarly  situated  and 
with  similar  constitutions.      They   lived  rather   more  than 
half  a  mile  from  the  river,  and  on  an  elevation  from  which 
there  was  a  descending  slope  of  about  a  hundred  feet  to  the 


238  PHYSIOLOGY    AND    HEALTH. 

water.  As  soon  as  they  could  see  daylight,  during  the 
colder  months  of  their  bathing,  they  ran  down  this  slope  to 
the  water's  side,  undressed,  and  plunged  in  immediately; 
and,  after  remaining  a  few  minutes,  they  came  out  of  the 
water,  dried,  rubbed,  and  dressed  themselves,  and  then  ran 
back  to  their  home,  as  they  said,  "  in  a  delightful  glow." 

576.  The  same  principle  directs  us  to  warm  ourselves 
well  before  going  abroad  in  winter.  There  is  no  ground 
for  fear  of  taking  cold  by  going  from  a  warm  room  to  the 
cold  air,  if  the  body  is  properly  clothed,  or  if  the  exercise 
abroad  is  sufficiently  vigorous.  The  practice  of  some  to 
cool  the  body  partially  before  going  out  in  the  winter,  so 
that  the  changes  shall  be  neither  great  nor  sudden,  is  alto- 
gether needless  and  unphilosophical.  Let  one  sit  for  a  time 
in  a  cool  room,  and  reduce  his  temperature  as  low  as  he 
can  bear  it,  without  much  discomfort,  and  then  go  abroad 
into  the  colder  air,  and  he  will  begin  to  suffer  much  quicker, 
and  be  much  more  liable  to  take  cold,  than  another  who  has 
been  sitting  in  a  well-warmed  room,  and  goes  out  into  the 
cool  air,  with  a  comfortable  heat  in  his  body. 


CHAPTER    XVI. 

Nervous  Sensibility  increased  by  Bathing.  —  Sense  of  Touch  made 
more  acute.  —  Nervous  System  affected  through  the  Skin.  —  We 
must  aid  the  Skin  in  the  Performance  of  its  Functions. 

577.  Another  effect  of  bathing  is  to  heighten  the  ner- 
vous sensibility.  The  whole  human  surface,  amounting  to 
fifteen  square  feet,  being  bespread  with  the  terminations  of 
the  innumerable  nerves,  exposes  a  wider  extent  of  the  ner- 
vous system  to  the  influence  of  external  substances  than  any 
other  organ ;  and  through  this  the  body  receives  stronger 
and  severer  impressions  than  through  any  other  avenue.  An 
injury  to  the  eye,  the  nose,  or  the  ear,  is  generally  limited 
in  its  consequences  to  the  injured  organ  :  this  may  be  de- 


THE    SKIN.  239 

stroyed,  while  the  rest  of  the  body  remains  sound ;  but  a 
burn  upon  the  skin  —  certainly  one  that  covers  the  entire 
surface,  though  not  deep,  and  even  slight  — •  is  fatal. 

578.  If  this  great  extent  of  skin  is  covered  with  the  gath- 
ered excretions  of  days,  and  months,  and  years,  —  if  its  pores 
and  its  excretory  apertures   become   filled,  and  the  surface 
agglutinated  with  the  compound  of  perspiration,  and  oil,  and 
dust,  —  the  sensibility  of  the  nervous  extremities  must  be 
blunted,  and  the  power  of  receiving  impressions  materially 
diminished.     But  when  the  skin  is  cleansed  and  unburdened 
of  its  load  of  impurities,  these  nervous  points  are  more  free 
to  receive  impressions,  and  are  more  easily  acted  upon  by 
external  objects ;  the  skin  has  then  a  more  lively  sensibility 
to  pleasure  and  pain,  to  heat  and  cold,  an(J  a  keener  sense 
of  touch.     The  blind  would  not  attempt  to  read  his  raised 
letters,  nor  the  draper  to  discriminate  the  qualities  of  cloth, 
with  soiled  fingers ;   nor  would  the  accomplished  performer 
play  on  his  violin  with  unwashed  hands. 

579.  Laura  Bridgman,  whose  senses  of  sight  and  hearing 
are  lost,  has  a  most  delicate  sense  of  touch.     The  increased 
sensibility  of  her  skin  compensates,  in  good  measure,  for  her 
other  privations,  and  enables  her  to  maintain  a  fastidious  neat- 
ness of  person  and  dress.     Nothing  of  the  kind  can  exceed 
the  purity  of  her  skin,  or  the  acuteness  and  liveliness  of  her 
cutaneous  sensations.     She  has,  therefore,  the  nicest  power 
of  discerning  and  comparing  minute  objects.     She  can,  with 
unusual   correctness,  discriminate   the  various   textures   of 
cloths,  and  distinguish  the  different  degrees  of  fineness  of 
dresses.      She  enjoys   the   delicacy   of  workmanship   upon 
wood  and  metals,  and  discovers  the  cleanness  and  uncleanness 
of  her  clothing.    Few  detect  more  readily  any  blemish  upon 
her  garments,  or  seem  to  be  more  averse  to  wear  unwashed 
linen,  or  more  desirous  to  enjoy  the  change  of  the  worn  for 
the  fresh  dresses  from  the  laundry. 

580.  Some  produce  the  greatest  effect  on  the  nervous  sys- 
tem through  this  avenue  of  the  skin.     Esquirol,  one  of  t!ie 
ablest  writers  upon  insanity,  and  the  physician  in  a  very  large 


240  PHYSIOLOGY  AND   HEALTH. 

Lunatic  Hospital  in  Paris,  calms  the  excitement  of  the  furi- 
ous maniac  by  pouring  cold  water  over  the  whole  surface  for  a 
considerable  period,  and,  by  thus  cooling  the  skin,  depresses 
the  external  nervous  system,  and,  through  this,  tranquillizes 
the  agitated  brain.  This  method  is  practised  with  wonder- 
ful success  in  his  hands,  and  is  elsewhere  found  to  have  a 
similar  effect  upon  many  excited  patients. 

581.  Such  is  the  structure  of,  and  such  are  the  offices 
performed  by,  the  skin.     We  have  seen  that  the  former  is 
complicated,  and  the  latter    are  numerous.     It  is  manifest 
that  this  whole  organ  is  intimately  connected  with  the  oper- 
ations of  all  the  other  organs,  and  that  the  freedom  of  action, 
the  health,  and  the  very  life  of  the  inner  man,  depend  very 
materially  upon  the   healthy  condition  of  the  outer   man. 
We  have  seen,  also,  that  this  organ,  while  it  is  ready  to  per- 
form its  own  part  well,  cannot  do  it  alone,  but  stands  in  need 
of  our  direction  and  aid  to  help  it  in  its  work,  and  our  faith- 
ful watchfulness  to  guard  it  from  suffering  and  evil. 

582.  We  have  therefore  a  responsibility  to  sustain  in  re- 
gard to  the  skin.     We  must  bathe  it,  and  purify  it  from  all 
foulness,  and  cleanse  it  from  all  the  excretions  that  adhere 
to  it ;  we  must  give  it  tone  and  vigor,  and  power  of  resist- 
ance to  external  injury,  and  make  it  more  capable  of  receiv- 
ing  impressions  and  conveying  sensations ;  and,  lastly,  we 
must  clothe  it,  and  otherwise  defend  it  from  excessive  radia- 
tion of  heat,  and  over-active  evaporation,  which  would  cool 
the  body  below  its  healthy  and  natural  temperature;  and  yet 
we  must  not  so  overclothe  it  as  to  lessen  its  power  of  self- 
protection. 


BONES,  MUSCLES,  EXERCISE  AND  REST.      241 

PART   VI. 

BONES,  MUSCLES,  EXERCISE  AND  REST. 


CHAPTER  I. 

Bones,  Composition  of.  —  Flexible  in  Childhood.  —  Brittle  in  Old 
Age.  —  Strongest  in  Middle  Life. —  Supplied  with  Blood- Vessels 
and  Nerves.  —  Subject  to  Growth  and  Decay .-—  Grow  strong  by 
Use.  —  Should  be  used  cautiously  in  Childhood.  —  Rickets. 

583.  The  bones  are  hard,  stiff,  and  very  strong.     They 
are  externally  solid,  Jbut  are  somewhat-hollow  within.     They 
are  composed  of  _such  materials,  that,  without  being  heavy, 
they  are  very  firm,    and   formed  in  such   a  manner,  that, 
without  being  large  or  clumsy,  they  are  very  strong.     The 
composition  of  the  bones  is  twofold  —  the  earthy  and  the 
animal.     The  earthy  part  of  the^bones  is  lime,  or  rather  a 
phosphate  of  lime^    This^gives  them  solidity  and  firmness. 
The  animal  part  is  composed  of  gelatine,  which  is  a  sub- 
stance similar  to, glue.     This  gives  the  bonss  their  strength 
and  life.     Either  of  these  alone  would  make  imperfect  and 
weak  bones. 

584.  When  these  two-  elements  —  the  Ijme  and  the  gela- 
tine —  are    united    in   due  .proportions,  the  bones  are  very 
strong,  and  will  bear  very  Heavy  shocks ;  but,  if  either  is 
deficient,  the  body  is  not  supported.     When  the  lime  is  de- 
ficient, the  bones  will  bend ;  and,  .when  the  gelatine  is  defi- 
cient, they  will    break.     We  see  these  different  conditions 
of  the  bones  in  the  different  periods  of  life.     In  early  in- 
fancy, the  gelatine  predominates,  and  the  bones  are  soft  and 
yielding.     They  are  then  easily  bent,  but  not  easily  broken. 

21 


242  PHYSIOLOGY    AND    HEALTH. 

585.  As  the  child  grows,  the  lime  is  added,  and  the  bones 
become  stronger,  until  the  full  maturity  of  life,  when  the 
composition  is  the  most  perfect  and  the  frame  has  the  great- 
est power  of  resistance,  and  will  bear  the  hardest  blow  and 
support  the  greatest  burden  without   suffering.     This  state 
continues  until  the  approach  of  old  age.     Then  the  gelatine 
diminishes  and  the  lime  preponderates ;    the  bones   conse- 
quently become  brittle,  and  are  more  easily  broken. 

586.  The  bones  are  supplied  with  blood-vessels  and  blood; 
they    are    subject    to    growth    and   jdecay,    to    deposition 
of  new  matter  and  absorption  of  the  old  particles,  as  the 
other  textures  are.     The  change  is   shown   in  the   experi- 
ment of  feeding  sheep  with  some  coloring  matter.  (§  248, 
p.  114.)     The  bones  of  these  animals  were  red  while  they 
ate  madder,  and  became  white  when  they  returned  to  the 
usual  food  of  hay  and  grain.     In  the  first,ca§e,  the  red  par- 
ticles of  the  food  were  deposited  in  the  bpnes  unchanged. 
In  the  second,  these  red  particles  had  been  absorbed,  and 
others,  of  the  natural  color,  had  been  deposited  in  their  stead. 
The  bones  are  supplied  with  nerves,  and  are  therefore  sus- 
ceptible of  pain  under  some  circumstances.     In  some  states 
of  disease,  the   patient   complains   of  pain    in   his   bones. 
When  the  bone  is  sawed  in  amputation,  it  does  not  seem 
to   suffer ;    but,   if   it   becomes   inflamed,  the  pain    is   very 
severe. 

587.  When  a  bone  is  broken^and  the  parts  divided,  the 
textures  of  the  severed  ends  repair,  the  breach.     They,  in 
the  first  place,  throw  out  at  the  broken  extremities  a  quantity 
of  adhesive  matter.     This  unites  the  parts  with  a  soft  bond, 
which  would  prevent  their  being  drawn  asunder,  but  would 
not  prevent  their  bending  at  this  place.     After  this  flexible 
union    is    formed,    the    blood-vessels   throw    into   it    earthy 
matter,   which  combines  with  the  jelly,  and   forms  a  new 
bone,  of  composition  similar  to  that  of  the  original   bone. 
At  first,  this  new  structure  is  not  quite  so  firm  as  the  old  ; 
but  nature  provides  for  this  by  increasing  the  quantity  of  new 
deposit,  and  making  a  bulbous  projection  all   around ;  thus 


BONES,  MUSCLES,  EXERCISE,  AND  REST.     '243 

the  bone  is  at  the  place  of  junction  larger  than  either  portion 
of  the  shaft,  above  or  below.  When,  in  the  lapse  of  time, 
this  new  bone  becomes  condensed,  and  as  strong  as  the  old 
bone,  then  the  external  deposit  is  absorbed,  and  the  whole 
shaft  is  nearly  restored  to  its  original  form. 

588.  The  process  of  absorption  and  deposition  of  the  par- 
ticles of  bone  is  shown  in  their  change  of  shape ;  as  when 
a  tumor  or  enlargement  of  the  arteries  presses  upon  the  ribs 
within,  and  causes  some  parts  of  them  to  spread ;  or  as  when 
the  close  dresses  press  upon  the  same  bones  without,  they 
contract  to  meet  the  necessity  of  the  case.  (§  340,  p.  150.) 

589.  The  bones  grow  larger  and  stronger  by  use,  like  the 
other   systems.      Exercise   of   the   parts   quickens    the   cir- 
culation and  increases  their  nutriment.     Disease  and  inaction 
weakens  them.     If  any  one  in  good  healtn*  should  lie  upon 
his  bed  for  a  long  period,  —  months  or  years, —  at  the  end  of 
this  time  he  would  not  find  it  easy  even  to  stand.    The  bones 
would  not  easily  support  his  weight.     The  exercise  of  the 
bones  favors  the  deposition  of  the  earthy  particles ;  and  for 
this  reason  the  bones  of  the  laborer   are  dense  and  hard. 
They  have  the  due  proportion  of  the  animal  matter  and  of  the 
earthy  matter  in  their  composition,  and  have,  consequently, 
great  strength.     But  those  who  are  unaccustomed  to  labor, 
or  even  exercise,  have  not  the  full  proportion  of  lime  in  their 
bones,  nor  the  strength  that  belongs  to  the  working  man. 

590.  The  bones  in  early  life,  being  more  gelatinous  and 
earthy,  are  consequently  weak ;  and  the  child,  although  able 
to  exercise,  is  incapable  of  hard  labor.     If  he  is  put  to  hard 
work,  the  deposition  of  the  earthy  matter  is  hastened,  and  the 
bones  become  consolidated  before  they  attain  their  full  size ; 
and  the  boy,  not  being  allowed  sufficient  time  for  growth,  be- 
comes a  stunted  man.     The  bones  of  the  child  require  more 
care  for  their  shape  and  their  growth  than  those  of  the  man  ; 
and  if  not  supported,  or  if  made  to  bear  too  great  weight, 
they  are  liable  to*  become  distorted.     In  sitting,  the  child 
should  either  find  rest  for  the  entire  thigh  bone,  from  the  hip 
to  the  knee,  upon  his  chair  or  bench,  or  the  lower  part  should 


244 


PHYSIOLOGY    AND    HEALTH. 


be  supported  from  the  knees  and  the  legs  by  the  feet  resting 
upon  the  floor.  Too  many  of  the  school-rooms  are  furnished 
with  seats  built  upon  one  uniform  model  and  of  the  same 
height.  If  these  are  high  enough  for  the  older  and  larger 
children,  they  are  too  high  for  the  younger  and  smaller. 
When,  therefore,  these  sit,  the  lower  leg  and  foot  hang  from 
the  lower  part  of  the  thigh,  which  projects  beyond  the  seat, 
and  may  cause  it  to  suffer.  (Fig.  XXX.)  The  weak  bones 


FIG.  XXIX. 


FIG.  XXX. 


of  this  age  do  not  well  bear  long  continuance  of  any  posture ; 
the  attitudes,  therefore,  should  be  very  frequently  varied. 

591.  This  process  of  consolidating  the  bones  from  infancy 
to  old  age  is  gradual,  and  is  one  of  the  evidences  of  good 
health.     But  in  some  feeble  persons  the  lime  is  not  deposited 
in  the  usual  proportion,  and  the  gelatine  prevails  through  life, 
as  in  childhood ;  this  is  the  disease  familiarly  known  as  the 
rickets.     The  bones  are  then  weak,  and  liable  to  be  bent. 
The  heads  of  such  bones  are  generally  enlarged  and 'misshapen, 
and  the  shafts  frequently  crooked.     The  spine  is  curved,  and 
sometimes  the  skull  is  enlarged.     This  disease  happens  mostly 
among  those  who  are  badly  nourished,  who  have  poor  and 
insufficient  food,  who  live  in  damp  and  dark  rooms  or  hovels, 
and  breathe  foul  air. 

592.  The  bones  are  not  solid.     Their  inner  parts  are  loose 


BONES,    MUSCLES,    EXEECISE,    AND    REST. 


245 


and  porous,  but  the  external  layers  are  arranged  in  cells, 
like  a  honey-comb.  This  is  the  most  observable  in  the  heads 
of  the  long  bones,  as  in  that  of  the  thigh,  (Fig.  XXXI.) 
This  arrangement  gives  the  bones  the  greatest  strength 
with  the  least  weight. 

FIG.  XXXI.    Head  of  the  Thigh  Bone  sawed  open. 


a,  a,  Outer  layer  of  the  bone. 

6,  6,  Inner,  or  honey-comb  structure. 


CHAPTER  II. 

Skeleton.  —  Number  of  Bones.  —  Head.  —  Chest.  —  Spine.  —  Verte- 
brse.  —  Cartilages.  —  Pelvis. 

593;   The  skeleton  (Fig.  XXXII.)  is  .composed  of  two  hun- 
dred and  forty-six  bones,  including  the  teeth  and  the  parts  of 
the  head*    Some  of  these  bones  are   thin  and   flat,  as  the 
shoulder-blade,  (Fig.  XXXVII.,)  and  the  parts  of  the  head. 
21* 


246 


PHYSIOLOGY   AND    HEALTH. 


Some  are  long  and  flat,  as  the  ribs,  (Fig.  XV.)  The  bones 
of  the  arms  and  legs  are  long  and  roundish.  The  vertebrae, 
(Fig.  XXXIV,)  or  the  parts  of  the  spine^and  the  bones  of 
the  wrist  (Fig.  XXXVIII.)'  and  ankle,  (Fig.  XL.,j  are  more 
compact.  The  bones  of  the  pelvis  (Fig.  XXXII.j  are  irregular 

FIG.  XXXII.    Skeleton. 


a,  Head,  or  cranium. 

b,  b,  Chest. 

c,  c,  Back-bone,  or  spine. 

d,  d,  Pelvis. 

e,  Breast-bone,  or  sternum. 

f,  f,  Ribs. 

g,  g,  Collar-bone,  or  clavicle. 

A,  h,  Upper  arm-bone,  or  humerus. 

t,  i,  Bones  of -the  forjs  arm. 

k,  kt  Bones  of  the  hands  and  fingers. 

/,  7,  Thigh-bone,  or  femur. 

m,  m,  Bones  olthe  leg. 

n,  n,  Bones  of  the  foot. 


in  shape.  The  bones  have  various  projections,  which  serve 
for  the  attachment  of  the  muscles,  and  apertures  for  the 
blood-vessels  and  nerves  to  pass  through  ;  and  all  are  made 
to  fit  their  places  in  the  structure,  and  fulfil  their  purposes  in 
the  animal  economy. 


BONES,     MUSCLES,     EXERCISE,     AND    REST 


247 


594.  The  skeleton  is  divided  into  the  head,  the  trunk,  and 
the  upper  and.  lower  extremities.  The  trunk  includes  the 
spine,  or  the  back-bone,  the  ribs,  the  breast-bone,  and  the 
pelvis.  The  hec(d  is  composed  of  the  eight  bones  of  the  skull, 
the  fourteen  bones  of  the  face,  and  the  six  little  bones  of  the 
ears.  The  eight  bones  of  the  skull  are  arranged  to  form  a 

FIG.  XXXIH.    Bones  of  the  Head. 


a,  Frontal  bone. 

b,  Parietal  or  side  bone. 

c,  Occipital  bone. 
dt  Temporal  bone. 

e,  Nasal  bone  in  the  nose. 


/,  Malar,  or  cheek  bone. 
g,  Upper  jaw. 

h,  Thin  bone  below  the  eye. 
t,  Lower  jaw. 


hollow  box,  to  contain  the  brain.  They  are  united  and  held 
together  by  avsort  of  dove-tailed  joint,  (Fig.  XXXIII.)  This 
arrangement  and  utiion  of  these  bones  give  great  strength  to 
the  skull,  and  enable  it  to  bear  heavy  blows  without  break- 
ing. The  brain  has,  therefore,  a  secure  resting-place. 

595.  The  chest-  is  composed  of  twelve  of  the  vertebrae,  or 
bones  of  the  spine,  the  twenty-four  ribs,  and  the  breast-bone, 
(Fig.  XV.)  The  spine  or  back-bone  is  composed  of  twenty- 
four  distinct  bones,  callejd  vertebras.  Each  vertebra  consists 
of  a  body-,  a  ring,  and  various  processes  or  projections, 


248 


PHYSIOLOGY  AND    HEALTH. 


(Fig.  XXXIV.)  These  are  placed  one  upon  another,  from 
the  pelvis,  at  the  bottom  of  the  back,  to  the  head,  on  the 
top  of  the  neck.  These  bones  vary  in  thickness,  from 
about  an  inch  in  the  Joins,  to  about  a  quarter  of  an  inch  in 
the  neck. 

FIG.  XXXIV.     Vertebra  of  the  JVecfc. 


a,  Body  of  the  bone,  upper  surface. 

b,  Ring. 

c,  Process  of  bone  extending  back- 
ward. 

d,  Front  surface  of  the  bone. 

e,  e,  Processes  extending  to  the  right 
and  left. 


596.  There  are  seven  of  these  bones  in  the  neck,  called 
cervical  vertebra.  These  are  thin,  and  have  long  project- 
ing or  spinous  processes  extending  directly  backward,  (Fig. 
XXXIV.  c.)  There  are  twelve  bones  in  the  back,  against  the 
chest.  These  are  called  dorsal  vertebra.  They  are  con- 

FIG.  XXXV.     Vertebra  of  the  Back.    (Side  View.) 


a,  Body  of- the  bone. 

b,  c,  Processes  of  bone  extending 
backward. 


nected  with  the  ribs.     Their  long  spinous  processes  extend 
downward,  (Fig.  XXXV.  c.)     The  other  five  are  called  lum- 


BONES,    MUSCLES,     EXERCISE,    AND    REST.  249 

bar  vertebra.  These  are  in  the  hollow  of  the  back,  between 
the  pelvis  and  the  chest.  They  are  very  thick,  and  have 
short,  club-shaped  spinous  processes,  that  extend  directly 
backward.  These  processes  can  be  felt  through  the  skin. 

597.  Between  these  vertebrae  are  layers  of  very  tough  and 
elastic  cartilage,  which  adhere  very  firmly  to  the  bones,  and 
hold  them  together.     These  layers  are  very  thick  in  the  loins, 
and  thin  in  the  neck.     They  are  capable  of  compression  and 
expansion,  like  India  rubber.     They  may  be  compressed  on 
one  side  and  stretched  on  the  other  at  the  same  time.    When 
we  bow,  these  cartilages  are  pressed  and  flattened  on  the  front 
side,  and  stretched  and  thickened  on  the  opposite  side.    In  this 
way,  we  bend  the  back  in  any  direction,  and  the  spinal  column 
is  made  exceedingly  flexible  with  this  succession  of  joints. 
This  cartilage  is  very  strong,  and  capable  of  sustaining  great 
weights.     The  head,  the  arms,  the  chest,  and  most  of  the  ab- 
domen  rest  upon,  and  are  supported  by, the  spine.     All  this 
weight  resting  upon  the  back-bone  from  morning  till  night, 
while  the  body  is  in  an  erect  position,  brings  so  much  pres- 
sure upon  these  intefvertebral  cartilages,  especially  those  at 
the  lower  part  of  the  spine,  that  they  become  somewhat  flat- 
tened in  the  course  of  the  day,  and  thereby  the  length  of  the 
spine  is  diminished,  and  a  man  is  from  a  half  to  a  whole  inch 
shorter  at  night  than  he  is  in  the  morning.     But  as  soon  as 
the  body  is  placed  in  a  horizontal  position,  and  the  pressure 
taken  from  the  cartilages,  they  begin  again  to  expand,  and  the 
column  recovers  its  length,  and  the  man  regains  his  ordinary 
height  by  morning.     Nevertheless,  the  continued  pressure  of 
the  weight  of  the  upper  part  of  the  body  overcomes,  in  some 
degree,  the  elasticity  of  the  cartilages  in  the  course  of  a  long 
series  of  years,  and  a  man  is  consequently  somewhat  shorter 
in  old  age  than  in  his  youth. 

598.  The  bones  of  the  spine  are  arranged  so  as  to  form  a 
column  with  a  double  curve,  somewhat  like  the  Italic  f.     At 
its  lower  end  it  is  curved  oujtward ;  as  it  ^ascends  it  is  curved 
inward  at  the  loins,  and  forms  the  hollow  of  the  back ;  again, 
it  is  bent  outward  at  the  upper  part  of  the  back  to  enlarge 


250 


PHYSIOLOGY    AND   HEALTH. 


the  chest  and  give  room  for  the  lungs ;  and,  finally,  at  the 
FIG.  XXXVI.     neck  it   is  erect.     Notwithstanding  these 

Spine,  or  Back-bone,  curves,  the  top  of  the  spine,  the  resting- 
place  of  the  head,  is  vertically  over  the 
sacrum,  on  which  the  last  bone  of  the 
spine  rests.  This  arrangement  of  the 
bones  of  the  spine  gives  this  column 
great  strength  and  flexibility. 

599.  The  pelvis  forms  the  base  of  the 
trunk,  (Fig.  XXXII,  rf.)  It  is  composed  of 
three  bones  —  the  two  hip  bones  and  the 
sacrum,  which  is  apparently  a  continua- 
tion of  the  spine.  These  bones  are  spread 
out  to  form  a  sort  of  basin,  on  which  the 
abdomen  rests.  The  spine  stands  on  the 
sacrum,  and  the  thigh  bones  are  attached 
to  the  hip  bones. 


a,  Resting-place  of  the  head. 
a,  b,  Seven  cervical  vertebrae. 
c,  d,  Twelve  dorsal  vertebrae. 
if  e,  f,  Five  lumbar  vertebras. 

ff>  <7»  <7»  Spinous  processes. 
h,  h,  Intervertebral  cartilages. 
t,  Sacrum,  a  part  of  the  pelvis. 


CHAPTER    III. 

Upper  Extremity.  —  Arm.  —  Wrist.  —  Hand.  —  Lower  Extremity.  — 
Leg.  —  Foot.  —  Arch  of  the  Foot.  —  Shape  of  the  Foot.  —  Natural. 
—  Deformed. 

600.  THE   upper   extremity   includes    the   collar-bone   or 
clavicle,  the  shoulder-blade,  upper  arm,  fore-arm,  wrist,  hand, 


BONES,    MUSCLES,    EXERCISE,    AND    REST. 


251 


and  fingers.  The  shoulder-blade  or  scapula  (Fig.  XXXVII.) 
is  a  broad,  thin  bone,  of  triangular  shape.  It  lies  flat  on  the 
back  of  the  chest,  imbedded  in  the  flesh,  and  held  in  its 

Fm.  XXXVn.    Shoulder-Blade,  or  Scapula. 


a,  Socket  for  the  head  of  the 
bone  of  the  upper  arm.  These 
form  the  shoulder  joint. 

6,  Border  of  the  shallow 
socket. 


place  by  the  muscles.  It  has  no  direct  attachment  to  the 
trunk,  but  at  its  upper  and  outer  corner  it  is  connected  with 
the  collar-bone.  At  this  upper  and  outer  corner  it  has  a 
shallow  socket  for  the  head  of  the  bone  of  the  arm. 

The  collar-bone  or  clavicle  (Fig.  XXXII.  g-,  g)  extends 

FIG.  XXXVIII.     Bones  of  the  Wrist. 


a,  Radius. 
6,  Ulna. 

c,  c,  c,  c,  Bones  of  the  wrist. 

d,  d,  d,  d,  Bones  of  the  hand. 

e,  Thumb. 


from  the  upper  end  of  the  breast-bone  to  the  upper  and  outer 
corner  of  the  shoulder-l)lade.  It  keeps  the  shoulder  in  its 
place. 


252 


PHYSIOLOGY    AND    HEALTH. 


The  upper  arm  has  a  single  bone,  the  humcncs,  (Fig. 
XXXII.  h.)  The  fore-arm  has  two  bones,  the  radius  and  the 
ulna,  (Fig.  XXXII.  i.)  The  wrist  has  eight  bones,  (Fig. 
XXXVIII.  c,  e,  c,  c,)  which  are  held  so  firmly  together  by 
ligaments  that  they  are  rarely  displaced.  The  hand  is  com- 
posed of  four  bones,  to  which  the  fingers  are  attached,  and 
the  bone  to  which  the  thumb  is  fixed,  (Fig.  XXXIX.)  These 

FIG.  XXXIX.    Bones  of  the  Hand. 


a,  Wrist. 

b,  b,  Hand. 

c,  c,  c,  c,  Fingers. 

d,  Thumb. 


are  held  more  loosely  together  by  ligaments,  and  enclosed  in 
one  sheath  of  skin.  Thejingers  are  each  composed  of  three 
bones,  (Fig.  XXXIX.  c,  c.)  The  hand  is  beautifully  and 
skilfully  arranged  and  adapted  to  an  almost  infinite  variety 
of  purposes.  Its  wonderful  structure  and  multiplied  uses 
are  suited  to  the  exigencies  of  the  mind  which  directs  it, 
and  gives  to  man  a  superiority  over  all  other  animals. 

601.  The  lower  extremity  (Fig.  XXXII.)  is  composed  of 
the  thigh-bone,  which  is  a  single  shaft,  the  knee-pan,  the  two 
bones  of  the  leg,  the  bones  of  the  ankle,  foot,  and  toes. 
The  foot  (Fig.  XL.)  is  composed  of  twelve  bones.  Seven  of 
these, bones  are  of  irregular  shape,  and  are  arranged  to  form 
the  ankle  and  the  arch,  (Fig.  XL.  «,  6,  c,  d,  c,/,  g.)  The 
other  five  bones  are  long.  They  are  joined  to  the  instep 


BONES,    MUSCLES,    EXERCISE,    AND    REST. 


253 


behind,  and  support  the  toes  in  front.  The  great  toe  has  two 
bones,  and  each  of  the  other  toes  has  three  bones,  corre- 
sponding to  the  bones  in  the  thumb  and  fingers. 

FIG.  XL.    Bones  of  the  Foot. 


a,  6,  c,  d,  e,  f,  g>  Bones  of  the  ankle 
joint. 

«*,  »,  Bones  of  the  anterior  part  of  the 
foot. 

k,  Great  toe. 
I,  /,  Other  toes. 


602.  The  arch  of  the  foot  extends*  from  the  heel  to  the 
ball,  (Fig.  XLI.)     The  bones  are  exactly  adapted  to  each 

FIG.  XLI.    Arch  of  tint  Foot.    (Side  View.} 


a,  Bone  of  the  leg.  d,  d,  Instep. 

6.  Upper  bone  of  the  ankle.  e,  Great  toe. 

ct  Os  calcis,  or  heel  bone. 

other,  and  are  held  together  by  ligaments,  very  firmly,  but 
22 


254  PHYSIOLOGY  AND  HEALTH. 

not  immovably.  The  arch,  therefore,  is  not  unyielding  like 
the  skull,  but  it  is  somewhat  loose,  and  allows  a  little  spring 
to  the  foot  when  the  body  rests  upon  it.  This  arrangement 
gives  to  the  foot  both  strength  arid  elasticity.  It  admits  great 
ease  of  motion,  and  saves  the  jar  that  would  otherwise  hap- 
pen, when  we  step  upon  the  ground.  The  foot  rests,  not 
upon  its  whole  under  surface,  but  upon  the  heel  and  the  ball 
near  the  toes,  which  are  the  ends  of  the  arch.  The  hollow 
of  the  foot  bears  none  of  the  weight.  The  bones  of  the  leg 
(Fig.  XLI.  a)  rest  upon  the  top  of  the  arch,  b. 

603.  When  we  step  the  hollow  of  the  foot  upon  a  round 
stick,  so  that  the  ends  of  the  arch  do  not  support  the  weight 
of  the  body,  as  when  walking  on  the  round  steps  of  a  ladder, 
or  when  a  boy  walks  on  stilts,  we  feel  an  unpleasant  jar,  and 
the  want  of  that  elasticity  and  ease  in  the  step  which  we 
feel  when  we  walk  naturally  on  a  flat  surface.     When  we 
walk,  we  first  place  the  heel  upon  the  ground  ;  this  receives 
a  part  of  the  shock  ;  next,  the  ball  comes  to  the  ground,  and 
the  force  or  weight  comes  upon  the  arch.     Thus  the  shock 
is  so  divided  that  it  is  hardly  felt. 

604.  When  we  jump  down  from  any  high  place,  we  throw 
the  toes  downward, 'so' that  the  first  force  of  the  blow  is  re- 
ceived upon  the  ball  of  the  foot.     The  ankle  then  bends,  and 
the  second  force  is  received  upon  the  heel ;  and  again  these 
two,  being  the  ends  of  the  arch,  yield,  and  thus  the  force  is 
divided  into  three  portions,  and  is  received  in  part  upon  the 
ball,  the  heel,  and  the  arch;  and  thus  no  violent  jar  is  com- 
municated to  the  general  frame  above.     A  sailor,  falling  from 
the  mast  in  a  rolling  ship,  struck  the  hollow  of  his  foot  upon 
the  railing,  and-  received  a  very  severe  shock  and  much  injury. 
But  another,  falling  the  same  distance,  struck  with  the  ball 
of  his  foot  upon  the  level  surface  of  the  deck,  and  received 
no  great  shock  and  suffered  no  material  damage. 

605.  The  natural  shape,  of  the  foot  is  somewhat  broad  in 
front,  with  the  toes  spread,  or,  at  least,  lying  loosely,  and  the 
inner  side  of  the  great  toe  in  a  line  with  the  heel  and  the 
ball.     The   greatest   length  of  the  foot  is  along  this  lane, 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  255 

(Fig.  XLU.)  This  gives  to  all  the  bones  freedom  of  motion, 
and  to  the  whole  foot  its  greatest  elasticity.  But  the  shoes 
that  are  usually  worn  are  narrowed  in  front  of  the  ball  of 
the  foot,  and  the  toes  are  rounded,  and  even  pointed  some- 
times. This  shape  carries  the  toes  inward  from  both  sides, 

FIG.-  XLII.  FIG.  XLIII. 

Natural  shaped  Foot.  Compressed  Foot. 


and  causes  some  of  them  to  override  others,  (Fig.  XLIII.) 
This  diminishes  the  freedom  of  motion,  the  elasticity  of 
action,  and  the  usefulness  of  the  feet,  and  creates  a  limping 
and  awkward  gait. 


CHAPTER  IV. 

Joints.  —  Hinge.  —  Elbow.  —  Knee.  — Ball  and  Socket.  —  Shoulder.  — 
Hip.  —  Cartilages.  —  Self-oiling  Apparatus.  —  Ligaments.  —  Cap- 
sules. —  Sprains.  —  Dislocations. 

606.  The  joints  unite  the  bones  together,  and  yet  allow 
them  to  play  upon  each  other.  They  are  so  strong  that  the 
bones  cannot  be  separated  without  great  violence,  yet  they  do 
not  interfere  with  their  motions  upon  each  other.  There  are 
various  kinds  of  these  joints,  suited  to  the  wants  of  the  several 
parts  in  which  they  are  placed. 

The  hinge  joint  allows  motion  in  only  one  direction,  for- 


256 


PHYSIOLOGY    AND    HEALTH, 


ward  and  backward,  as  in  the  elbow,  (Fig.  XLIV.,)  the  knee, 
(Fig.  XL VII.,)  and  the  connection  of  the  lower  jaw  with  the 
he"ad. 

FIG.  XLIV.   Elbow. 


a,  Bone  of  the  tipper- arm. 

b,  e,  Bones  of  the  fore-arm. 

c,  Inner  angle  of  the  joint. 

d,  Ligaments  of  the  joint. 


The  ball  and  socket  joint  is  composed  of  aJball  on  the  end 
of  one  bone,  and  a  cup  or  socket  in  the  other,  in  which  the 
ball  plays,  as  in  the  hip  joint,  (Fig.  XLV.  c,  c?,)  or  as  the 

Fm.  XLV.    Hip  Joint. 


a,  Hip  bone. 

b,  6,  Thigh  bone. 

c,Head  of  the  thigh 
bone. 

d,  Socket  in  the  hip 
bone. 

e,  Ligament  attached 
to  the  bottom  or  centre 
of  the    socket  and    the 
head  of  the  thigh  bone. 


shoulder,  or  the  attachment  of  the  thumb  to  the  hand.  This 
joint  allows  motion  in  every  direction,  forward  and  back- 
ward, upward  and  downward,  and  in  a  circular  manner. 

607.  The  thigh  bone  has  almost  a  globular  head  at  its  up- 
per extremity,  (Fig.  XLV.  c,)  which  is  fitted  into  a  very  deep 


BONES,  MUSCLES,  EXERCISE,  AND  REST.     257 

socket  in  the  side  bone  of  the  pelvis.  The  head  of  the  bone 
of  the  upper  arm  is  less  than  half  a  ball,  and  is  fitted  into  a 
very  shallow  socket  in  the  upper  corner  of  the  shoulder  blade, 
(Fig.  XXXVII.  a.) 

608.  The  head  is  connected  with  the  upper  vertebra  by  (i 
hinge  joint)  which  allows  it  to  .bend  forward  and  backward. 
The  upper  vertebra  has  a  ring  on  its  posterior  side,  in  which 
a  tooth  or  pin  from  the  second  vertebra  is  inserted.     This 
allows  the  first  vertebra  to  turn  upon  the  second,  as  a  gate 
turns  upon  a  hook-and-eye  hinge.     By  this  joint  we  turn  the 
head  from  side  to  side,  and  by  the  other  we  nod  and  lift  the 
head. 

The  cartilages  between  the  several  bones  of  the  spine  allow 
the  column  to  bend  in  every  direction. 

609.  The  head  of  every  bone  is  covered  with  a  very  dense, 
but  somewhat  elastic  cartilage,   which  is  sufficiently  soft  to 
break  the  force  of  pressure  or  jars  upon. the  bones,  but  not 
soft  enough  to  be  loose  and  interfere  with  the  movements  of 
one  bone  upon  another.     These  cartilaginous  facings  of  the 
joints  are  not  very  thick  —  not  more  than   a  sixteenth  or 
eighteenth  of  an  inch.     They  are  covered  with  an  exceed- 
ingly smooth  lining,  that  presents  the  most  polished  surface 
imaginable. 

610.  It  is  onejof  the  admirable  provisions  in  regard  to  the 
joints,  that  they  never  wear  out.     Though  they  are  in  such 
frequent  use,  and  exposed  to  so  much  pressure  arid  motion 
from  infancy  to  extreme  old  age,  even  eighty  or  ninety  years, 
yet  they  never  wear  out.     The  tough,  cartilaginous  coverings 
of  the  ends  of  the  bones,  and  the  delicate  and  glairy  facings 
of  the  joints,  are  as  thick  and  as  smooth  at  the  end  as  at  the 
beginning,  or  at  any  period  of  life.     These  substances,  if 
worn  at  all,  are  perpetually  renewed.     They  pass  through  the 
same  changes,  they  are  subject  to  the  same  death  of  particles 
from  exhaustion,  and  the  same  renewal  of  living  particles,  as 
the  other  organs  and  textures. 

611.  Not  only  do  these  joints  and  their  parts  wear  well, 
but  they  haw  a  perpetual  self -oiling  apparatus,  that  keeps 

22* 


253 


PHYSIOLOGY    AND    HEALTH. 


their  faces  always  moist  and  slippery.  This  is  the  living 
joint,  which  prepares  and  pours  out  this  oily  fluid,  as  the  skin 
pours  out  perspiration ;  and  if  the  joints  are  properly  used, 
and  in  good  health,  this  fluid  is  of  the  due  proportion  and 
consistency.  But  in  some  cases  of  disease  or  injury,  it  be- 
comes abundant,  and  fills  the  sac  of  the  joint,  as  a  bladder, 
with  water.  This  happens  most  frequently  in  the  knee,  from 
a  blow  or  a  strain.  Then  this  lining  membrane  takes  an  un- 
natural and  increased  action,  and  throws  out  much  more  fluid 
than  is  needed,  and  so  fills  the  sac  of  the  joint  that  the  knee 
is  swelled  and  lame. 

612.  The  ligaments  and  the  c apsides  Jiold  the  bones  together 
at  the  joints.  The  capsule  encloses  the  whole  joint :  it  sur- 
rounds the  end  or  the  seat  of  junction  of  each  bone,  and  is 

FIG.  XLVI.    Knee,  Capsule^and  Ligaments. 


a,  Tendon  of  the  great  muscle  of  the  thigh, 
attached  to  the  knee  pan. 

b,  Knee  pan. 

c,  Tendon  connecting  the  knee  pan  with  the 
bones  of  the  leg. 

d,  dt  Capsule  covering  all  the  joint. 

e,  f,  Lateral  ligaments  extending  from  the 
thigh  to  the  bones  of  the  leg. 

ff,  Thigh  bone. 

h,  i,  Bones  of  the  leg. 


attached  to  both.  In  the  knee,  (Fig.  XLVI.  J,  d,)  the  cap- 
sule surrounds-,  and  is  attached  to,  the  lower  end  of  the  thigh 
bone  :  it  passes  over  the  space  between  the  bones,  and  in  like 
manner  it  surrounds,  and  is  attached  to,  the  upper  ends  of  the 
bones  of  the  leg.  The  synovial  membrane  within  this  cap- 
sule prepares  and  throws  into  the  joint  the  synovial  fluid  that 
moistens  and  oils  it. 

There  are  other  ligaments  within  and  without  the  joints. 
Some  of  those  within  the  knee  are  seen  in  Fig.  XLVII.     The 


BONES,    MUSCLES,     EXERCISE,    AND    REST.  259 

wrist  (Fig.  XLVIII.)  and  the  ankle  are  supplied  with  a  great 
variety  of  ligaraentous  bands,  that  hold  their  small  bones  in 

FIG.  XLVII.    Knee  and  Internal  Ligaments. 


a,  Thigh-bone. 

b,  c,  Bones  of  the  leg. 

d,  e,  f,  Ligaments  connecting  these  bones 
together. 


their  several  places,  and  yet  allow  them  due  freedom  of  mo- 
tion. The  hip  joint  has  a  round  ligament,  which  is  attached 
to  the  bottom  of  the  socket  and  to  the  middle  of  the  head  of 
the  thigh  bone,  (Fig.  XLV.  e.) 

613.  These  capsules  and  ligaments  are  strong  and  inelastic. 
They  are  so  distributed  and   arranged    as  to  allow  all    the 
requisite  movements,  and  yet  to  retain  the  bones  in  their  re- 
spective situations.     When   they   are   exposed   to   great   or 
sudden  violence,  they  are  sometimes  strained,  and  some  of 
their  minute  fibres  are  broken.      Then  the  joint  is  said  to  be 
sprained,  and  requires  a  long  healing  process  for  restoration. 
This  happens  most  frequently  to  the  foot  and  ankle  from  any 
misstep  or  fall,  causing  a  greater  strain  upon  the  ligaments 
than  they  can  safely  bear. 

614.  A  bone  is  dislocated  or  thrown  out  of  joint  when  it  is 
exposed  to  still  greater  strains  or  violence.     The  shoulder  is 
more  liable  to  this -injury  than  any  other  joint.     The  cavity 
is  so  shallow,  that  when  the  arm  is  stretched  forward  or  back- 
ward,  and  any  pressure  or  blow  comes  upon  it  in  front  or  be- 
hind, it  has  little  power  of  resistance,  and  the  head  is  thrown 
out  of  its  socket.     Persons  falling  forward,  as  when  thrown 


260 


PHYSIOLOGY    AND    HEALTH. 


from  a  horse  or  a  carriage,  are  apt  to  throw  their  arms  out  to 
save  themselves ;  the  weight  of  the  body  comes  upon  the 

FIG.  XLVIII.    Ligaments  of  the,  Wrist  and  Hand. 


a,  a,  Bones  of  the  fore-arm. 

b,  b,  b,  Bones  of  the  hand. 

c,  c,  c,  Ligaments  of  the  wrist. 

d,  d,  Ligaments  of  the  hand. 


hand,  and,  of  course,  upon  the  arm  and  shoulder ;  the  force 
of  the  blow  presses  the  bone  backward,  and  sometimes 
thrusts  the  head  over  the  edge  of  the  socket. 


CHAPTER  V. 

Muscles.  —  Motive  Power.  —  Number.  —  Arrangement.  —  Action.  — 
Description  and  Use.  —  On  Front  of  the  Body.  —  On  Back.  —  On 
Side. 

615.  THE  bones  are  merely  the  framework.  They  are  the 
rigid  parts  upon  which  the  action  is  made,  but  they  have  no 
active  power.  All  the  motive  power  is  in  the  muscles.  These 
perform  all  the  motions  in  the  animal  body. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  261 

The  muscles  form  the  most  abundant  part  of  the  body. 
They  constitute  the  great  b.ulk  of  the  limbs,  the  back,  and 
neck.  They  cover  the  face  and  chest,  and  form  the  principal 
portion  of  the  walls  of  the  abdomen.  In  lower  animals,  they 
are  the  lean  meat  which  we  eat  upon  our  tables.  They  con- 
sist of  stringy  fibres,  that  usually  lie  parallel  with  each  other, 
and  are  fastened,  by  a  strong  whitish-looking  substance,  into 
bundles.  Each  bundle,  thus  fastened  together,  forms  one 
muscle. 

616.  These  muscular  fibres  have*  a  power  of  drawing  up  or 
contracting,  like  the  earth  worm ;  and  when  they  thus  con- 
tract, they  draw  their  ends  toward  each  other,  and  draw  to- 
gether or  move  toward  each  other  whatever  parts  or  bones 
may  be  fastened  to  these  ends. 

617.  All  the  parts  of  the  body  that  move  are  furbished  with 
some  ofthes&jmiscjlcs,  or  bundles  of  lean  flesh.    There  are  five 
hundred  and  twenty-seven  muscles  in  the  human  body.     Five 
hundred  and  fourteen  of  these  are  in  pairs,  being  the  same  on 
the  two  sides,  and  thirteen  others  are  single  muscles,  as  the 
heart,  &,c.     These  are  arranged  in  layers,  and  in  some  parts 
of  the  body,  as  on  the  back  and  the  large  limbs,  there  are 
several  layers  between  the  skin  and  the  bones.     Some  of  the 
outer  layers  are  shown  in  Figures  XLIX.,  L.,  and  LI.     The 
inner  layers  are  shown  in  Figures  LII.,  LIV.,  LV.,  and.  LVII. 

618.  The  cutaneous  rpuscle,  (Fig.  XLIX.  «,)  is  attached  to 
the  skin  and  flesh, of  the  cjieek  above,  and  of  the  neck  below. 
It  aids  in  drawing  the  mouth  downward. 

The  deltoid,  XLIX.  6,  or  triangular  muscle,  has  its  upper 
side,  or  ends  of  the  fibres,  attached  to  the  collar-bone  and 
shoulder-blade.  These  fibres  meet  in  a  point,  which  is  at- 
tached to  the  humerus  or  bone  of  the  upper  arm.  Its  front 
fibres  draw  the  arm  upward  and  forward  ;  its  back  fibres  draw 
the  arm  upward  and  backward  ;  and  all,  together,  lift  the  arm. 

The  biceps,  or  two-headed  muscle  of  the  arm,  XLIX.  c.  and 
LI.  b,  is  attached  above  to  the  shoulder-blade  and  the  upper 
part  of  the  humerus,  and  sends  a  cord  to  the  lower  arm  near 
the  elbow.  It  bends  the  elbow. 


PHYSIOLOGY    AND    HEALTH. 
FIG.  XLIX.     External  Muscles  of  the  front  Part  of  the  Body, 


,The  pronalor,  XLTX.  <f,  extends  from  the  inner  side  of 
the  arm  to  the  outer  bone,  and  rolls  the  arm  inward,  and 
turns  the  hand  downward. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  263 

The  supinator,  XLIX.  d,  LI  d,  extends  from  the  outer 
'  side  of  the  humerus  and  the  outer  bone  of  the  fore-arm  to  the 
inner  bone;  it  rolls  the  arm  outward,  and  turns  the  hand 
upv\  ard. 

The  flexors  of  the  wrist,  XLIX.  f,  Ji,  and  the  long  palmar 
muscle,  XLIX.  g,  extend  from  the  lower  end  of  the  upper 
arm,  and  send  tendons  to  the  bones  of  the  wrist  and  hand. 
They  bend  the  wrist. 

The  pectoral  muscle,  XLIX.  i,  is  attached  to  the  breast 
bone  and  to  some  of  the  ribs  in  front,  and  extends  back  to 
the  upper  and  inner  part  of  the  humerus.  It  moves  the  arm 
forward  and  upward  obliquely. 

The  external  oblique,  XLIX.  k,  LI.  i,  arises  from  the  edge 
of  eight  of  the  lower  ribs,  and  passing  downward  and  forward 
it  covers  the  abdomen  in  front,  and  is  attached  below  to  the 
pelvis.  It  supports  the  abdomen,  and,  by  its  contractions,  it 
presses  upon  its  contents  and  forces  them  and  the  diaphragm 
upward  in  expiration,  (§  286.) 

The  semilunar  line,  XLIX.  /,  and  the  tinea  alba,  XLIX.  mt 
or  white  band,  are  layers  of  gristly  matter  extending  from  the 
breast  bone  to  the  pelvis.  They  give  support  to  the  abdom- 
inal muscles. 

The  sartorius,  or  tailor's  muscle,  XLIX.  o,  LI.  m,  ex- 
tends from  the  hip  bone  over  and  in  front  of  the  thigh,  and  is 
joined  to  the  inside  of  the  bone  of  the  leg,  below  the  knee. 
It  aids  in  bending  the  thigh:  it  rolls  the  hip  joint,  and  lifts 
one  leg  over  the  other,  as  tailors  sit. 

The  gracilis,  XLIX.  q,  assists  the  tailor's  muscle. 

The  muscle,  XLIX.  p,  aids  in  turning  the  thigh  outward. 

The  psoas  and  iliac  muscles,  XLIX.  r,  u,  are  attached  to 
the  back  bone,  and,  passing  over  the  pelvis,  ar3  joined  to  the 
thigh  bone.  They  bend  the  thigh  on  the  trunk. 

The  pectineus  and  triceps,  or  three-headed  muscles,  XLIX. 
s,  t,  extend  from  the  front  part  of  the  pelvis  to  the  inner  side 
of  the  thigh  bone.  They  assist  in  bending  the  thigh,  and  in 
'rolling  it  outward.  . 

The  rtcpis,  }£LIX.  w,  LI.  p,  is  attached  to  the  front  part 


264  PHYSIOLOGY   AND   HEALTH. 

FIG.  L.    External  Muscles  qf  the  back  Part  of  the  Body. 


of  the  pelvis,  and  extends  along  the  whole  length  qf  the  thigh 
bone,  and  is  fixed  by  a  cord  to  the  knee  pan.  It  straightens 
the  knee,  and  lifts  the  body  upon  the  leg  when  sitting  down. 


BONES,    MUSCLES,     EXERCISE,     AND    REST.  265 

The  vastus  internus  and  externus,  XLIX.  v,  x,  LI.  n,  o, 
are  two  muscles  that  are  attached  to  almost  the  whole  length 
of  the  thigh  bone,  and  send  tendinous  bands  to  the  upper  end 
of  the  bones  of  the  leg.  They  assist  in  straightening  the  leg. 

619.  The  trapezius,  (Fig.  L.  a,  a,  LI./*,)  is  attached  above 
to  the  head,  and  the  bones  of  the  neck  and  back  :  it  extends 
outward  and  part  downward  and  part  upward,  and  its  op- 
posite end  is  attached  to  the  collar-bone  and  shoulder-blade. 
Its  upper  fibres  lift  the  shoulder ;  its  lower  fibres  draw  it 
downward  and  backward ;  and  its  middle  fibres,  and  the 
whole  acting  together,  draw  the  shoulder  backward. 

The  latissimus  dorsi,  or  the  broadest  muscle  of  the  back, 
L.  b,  LI.  g,  extends  from  the  middle  and  the  lower  half  of 
the  back  bone,  and  the  back  part  of  the  pelvis,  and  extends 
forward  and  upward  to  the  upper  arm  near  the  shoulder.  It 
draws  the  arm  backward  and  downward. 

The  deltoid,  L.  c,  XLTX.  b,  lifts  the  arm. 

The  triceps,  or  three-headed  extensor  of  the  fore-arm,  L.  d, 
is  attached  above  to  the  shoulder-blade  and  humerus,  and 
below  to  the  extreme  point  of  the  elbow.  It  straightens  that 
joint. 

The  great  glutens,  L.  e,  LI.  k,  extends  from  the  back  part 
of  the  pelvis  to  the  upper  part  of  the  thigh  bone.  It  straight- 
ens the  hip  joint,  and  raises  the  body  up  on  the  lower  limbs 
from  the  sitting  position. 

The  biceps,  or  two-headed  flexor  of  the  leg,  L.  f,  is  attached 
above  to  the  pelvis  and  the  thigh  bone,  and  sends  a  tendon 
from  its  lower  end  through  the  outside  of  the  ham  to  the 
outer  bone  of  the  leg.  It  bends  the  knee,  and  its  tendon 
forms  the  outer  ham-string. 

The  semitendinous  and  the  semimcmbranous  muscles,  L.  g^ 
Ji,  are  attached  above  to  the  lower  part  of  the  pelvis,  and,  ex- 
tending down  the  back  and  inner  part  of  the  thigh,  send  cords 
through  the  middle  of  the  ham  to  the  inner  bone  of  the  leg. 
They  aid  in  bending  the  knee,  and  their  tendons  form  the 
inner  ham-string. 

The  gastrocnemius,  or  great  muscle  of  the  calf,  L.  f,  is  at- 


2G6  PHYSIOLOGY    AND    HEALTH. 

FIG.  LI.    External  Muscles  on  the  side  of  the  Body. 


tached  above  to  the  back  of  the  thigh  bone,  and,  from  its  lower 
end,  sends  a  tendon  to  the  ankle.  It  straightens  the  ankle 
and  lifts  the  body  on  the  foot. 

620.  LI.  a.  Deltoid,  lifts  the  arm. 


BONES,    MUSCLES,     EXER 

1.  Biceps,  or  two-headed  flexor  of  thl 

c.  Brachial  muscle,  extends  from  the  middle  of  the  hume- 
rus  to  the  front  side  of  the  lower  arm.     It  aids  in  bending 
the  elbow. 

d.  Supinator,  turns  the  hand  upward. 

e.  Triceps,  or  three-headed  extensor  of  the  arm. 

f.  Trapczius,  draws  the  shoulder  upward,  backward,  and 
downward. 

g.  Latissimus  dorsi,  or  broadest  muscle  of  the  back,  draws 
the  arm  backward  and  downward. 

h.  Serratus,  or  saw-edged  muscle.  One  side  has  nine 
fleshy  teeth,  which  are  attached  to  the  upper  nine  ribs  in 
front :  the  opposite  edge  of  the  muscle  is  attached  to  the 
front  and  outer  edge  of  the  shoulder-blacjLe.  It  draws  the 
shoulder-blade  forward,  and  when  this  bone  is  fixed  by  the 
other  muscles,  it  aids  in  lifting  the  ribs. 

i.  External  oblique  of  the  abdomen,  aids  in  expiration. 
'  k.  Glutens  maximus,  or  great  gluteal  muscle,  straightens 
the  hip. 

I.  Glutens  medius,  or  middle  gluteal  muscle,  extends  from 
the  back  part  of  the  pelvis  to  the  back  and  outer  part  of  the 
thigh  bone.  It  draws  the  thigh  outward  and  backward,  and 
rolls  it  outward. 

m.  Sartorius,  or  tailor's  muscle,  crosses  the  leg. 

n.   Vastus  internus,  straightens  the  leg. 

o.    Vastus  externus,  straightens  the  leg. 

p.  Rectus,  straightens  the  leg. 

q.  Tendon  or  cord  forming  the  outer  ham-string. 

r.  Tendon  forming  the  inner  ham-string. 

s.  GastrocnemiuS)  forms  the  calf  of  the  leg,  and  straight- 
ens the  ankle. 


268  PHYSIOLOGY   AND    HEALTH. 


CHAPTER   VI 

Muscles.  —  Shape.  —  Attachment.  —  Situation.  —  Swell  in  Action.  — 
Arrangement.  —  Antagonism.  —  Cooperation. 

621.  THE  muscles  are  of  various  shapes,  and  their  fibres 
are  arranged  in  various  directions,  to  suit  the  wants  of  the 
places  where  they  are  to  operate,  and  the  convenience  of 
distribution.     On  the  limbs  they  are  long  and  roundish;  on 
the  trunk  they  are  mostly  flat.     Sometimes  the  fibres  are 
arranged  in  the  shape  of  a  fan,  the  broad  end  being  fixed 
to  an  immovable  bone  ;  and,  at  the  other  end,  all  the  fibres 
are  gathered  into  one  point,  and  are  fixed  to  a  movable  bone, 
as  in  the  deltoid,  (Fig.  XL1X.  &,)  and  the  trapczius,  (Fig. 
L.  «,)  (§§  618,  619.)     When  the  fibres  of  one  side  of  this 
fan-shaped  muscle  act,  they  draw  the  bone  in  that  direction  ; 
and  when  the  fibres  of  the  opposite  side  act,  they  draw  the 
bone  in  the  opposite  direction ;  and  when  they  all  act  together, 
they  draw  it  in  a  line  with  the  middle  fibres. 

622.  The  diaphragm   (§  273,  p.   124)  is  a  muscle,  and 
acts  by  the  same  contractile  power  as  the  muscles  of  the 
arms  and  legs.     But,  unlike  them,  it  is  attached  to  no  joint, 
and  moves  no  bone.     It  is  fixed  to  the  bottom  of  the  ribs, 
and  is  arched  up  into  the  chest.     (Fig.  XVII.)     Its  fibres, 
like  the  spokes  of  a  wheel,  extend  from  the  circumference 
to  the  centre  ;  and,  when  they  contract,  they  draw  the  centre 
and  the  whole  arch  downward  towards  the  line  of  attach- 
ment of  the  outer  edge.     This  descent  of  the  arch  leaves 
room  in  the  chest  for  the  expansion  of  the  lungs  and  the 
inspiration  of  air.     The  heart  (§  206,  p.  94)  is  a  hollow, 
muscular  bag ;  when  its  fibres  contract,  they  lessen  the  cavity 
within  and  expel  the  contents  of  blood.     The  muscular  coat 
of  the  oesophagus,  (§  23,  p.  17,)  the  stomach,  (§  28,  p.  20,) 
and   of  the    alimentary    canal,  winds   about   them,  and    is 
attached  to  no  fixed  point.     It  presses  upon  the  contents  of 
these  organs,  and  aids  the  digestive  operation  in  the  stomach, 
and  carries  the  contents  onward  through  the  channel. 


BONES,    MUSCLES,     EXERCISE,     AND    REST. 


269 


623.  These  muscles,  distributed  and  arranged  in  nature's 
most  skilful   and   benevolent  manner,  are  the  source  of  al) 
our  power  of  motion.     By  these  we  walk,  we  lift,  we  strike, 
we  eat  and  swallow,  we  breathe  and  cough,  we  speak,  wink, 
nod  the  head,  bend  the  back,  and  do  all  our  work.     A  pal- 
sied limb,  whose  muscular  power  is  lost,  is  as  motionless  as 
the  limb  of  the  dead. 

624.  The  muscles  are  mostly  attached  to  different  bones 
at  their  two  ends,  and  by  their  contractions  move  these  bones 
on  or  toward  each  other,  as  at  the  joints.     But  some  muscles 
are   intended   to   move   only  the  flesh,  and   are,  therefore, 
attached  only  to  the  flesh,  at  least  at  one  end,  as  in  the  face. 

FIG.  LII.    Muscles  of  the  Face. 


a,  Frontal  muscle,  raises  the 
eyebrows,  and  wrinkles  the  fore- 
head. 

b,  b,  Circular  muscles,    close 
the  eye. 

c,  d,   Muscles  that  raise  the 
corners  of  the  mouth. 

e,  Circular  muscle,  closes  the 
mouth. 

/,  /,  Muscles  that  draw  down 
the  lower  lip. 


The  muscles  (Fig.  LII.  «,  a)  that  wrinkle  the  forehead  and 
draw  up  the  eyebrows,  are  attached  to  the  bone  above,  and  to 
the  skin  and  flesh  below.  The  muscles  that  raise  and  draw 
down  the  corners  of  the  mouth  and  the  lips  (Fig.  LII.  c,  d,f) 
are  attached  to  the  bones  of  the  two  jaws  and  the  cheek  by 
one  end,  and  to  the  lips  by  the  other.  The  muscles  of  the 
eye  ball  (Fig.  LXVI1I.)  are  fixed  by  their  inner  ends  to  the 
bone  within  the  socket  of  the  eye,  and  by  their  outer  ends  to 
the  ball.  By  their  various  contractions  they  roll  the  eye. 
23* 


270 


PHYSIOLOGY    AND    HEALTH. 


Fm.  LIII. 


Some  are  circular,  as  those  that  close  the  mouth  and  eye, 
(Fig.  LIT.  6,  e.)  The  heart  has  no  attachments  ;  it  is  sus- 
pended in  the  chest,  and  acts  only  on  its  contents.  The 
muscular  coat  of  the  ossophagus,  stomach,  and  alimentary 
canal  surrounds  these  organs,  and,  by  its  contractions,  it 
forces  their  contents  onward. 

625.  The  muscles  are  not  placed 
directly  between  the  bones  which  are 
to  be  moved,  —  this  would  make  the 
joints  clumsy,  —  but  at  some  little  dis- 
tance, and  attached  directly  at  one 
end  to  one  bone,  and  then  generall-y 
fastened  to  a  tendon  or  cord  which 
moves  over  the  joint  to  the  other  bone. 
The  muscle  that  bends  the  elbow  (Fig. 
LIV.  d)  is  placed  entirely  on  the  front 
part  of  the  upper  arm.  The  upper  end 
of  this  is  fixed  to  the  upper  bone,  but  no 
part  of  the  muscle  touches  the  lower 
'arm.  A  cord  passes  from  the  lower 
end,  over  the  elbow-joint,  to  the  lower 
arm.  So,  also,  the  muscles  that  move 
the  hand,  the  knee,  the  foot,  &,c. 
Sometimes  the  muscle  is  placed  at  a 
considerable  distance  from  the  bone 
to  be  moved.  The  muscles  of  the 
fingers  are  placed,  not  on  the  hand, 
nor  even  on  the  wrist,  but  on  the 
fore-arm,  (Fig.  LIII.  «,  a,  a;)  and 
the  long  cords  or  tendons  (b,  b,  b) 
can  be  easily  felt  as  they  pass  along 
the  lower  part  of  the  fore-arm,  and 

over  the  wrist,  and  over  the  hand  to 

a,  a,  a.    The  fleshy  parts 

of  the  muscles.  tne  fingers.     By  a  similar    arrange- 

b,  b,  b.  Tendons  of  these  ment,  the  toes  are  moved  by  muscles 
muscles  passing  over  the  situated  on  the  leg.     The  cords  pass 
wrist  to  the  hand  and  fin-  through  groOves   or    pulleys    at  the 


BONES,    MUSCLES,    EXERCISE,    AND    REST. 


271 


ankles,   and  there  change  their  direction   and  pass  to  the 
toes. 

626.  When  the  muscles  draw  up,  they  increase  in  size,  and 
swell  out  at  their  middle;  and  when  they  cease  to  act,  they 
are  again  drawn  out  in  length,  and  their  size  is  reduced. 
If  we  place  the  right  hand  on  the  front  of  the  left  upper  arm 
when  we  bend  the  left  elbow,  we  shall  feel  the  biceps  muscle 
(Fig.  LIV.  c,  d)  swelling  out  and  becoming  hard.  If,  at  the 
same  time,  we  place  the  fingers  in  the  angle  of  the  elbow, 
we  shall  feel  the  cord  drawn  tight  and  moving.  If  we 
put  the  hand  on  the  same  place  when  we  straighten  the 
elbow,  we  shall  feel  the  muscle  growing  soft,  the  swelling 
going  down  on  the  upper  arm,  and  the  cord  moving  back- 
ward and  becoming  loose  in  the  elbow. 

FIG.  LIV.    Flexor  Muscle  of  tKe  Elbow. 


a,  Hum-eras,  or  bone  of  upper- 
arm. 

b,  Bone  of  fore-arm. 

c,  Hand. 

d,  Biceps  muscle. 

e,  Its  upper  attachment. 


/,  Its  cord  attached  to  the  lower 
arm. 

g,  Muscle  that  straightens  the 
elbow. 

h,  Its  attachment  to  the  elbow. 


627.  The  muscle  on  the  back  of  the  upper  arm  that 
straightens  the  elbow  is  broader  and  larger,  so  that  its  swell- 
ing, and  reduction  are  not  squperceptible  as  ,in  case  of  the 
bending  muscle.  Nevertheless,  its  .action  and  relaxation 
may  be  perceived,  when  the  lower  arm  moves  upon  the 


272  PHYSIOLOGY    AND    HEALTH. 

upper.  The  same  action  may  not  only  be  very  distinct- 
ly felt,  but  even  seen,  on  the  temple,  in  the  muscle  that 
closes  the  jaw.  The  upper  end  of  this  muscle  is  fixed  upon 
the  bone  of  the  temple,  and  passes  down  behind  the  project- 
ing arch  of  the  cheek-bone  to  the  upper  side  of  the  lower 
jaw.  When  it  contracts  and  draws  up  the  lower  jaw,  it 
swells  out  on  the  temple  so  prominently  that  its  increase  and 
diminution  are  seen  every  time  we  move  the  jaw,  either  in 
mastication  of  food  or  talking. 

628.  The   muscles    have    only    a  power    of  contraction. 
They  have  no  active  power  of  forcible  expansion.     They 
can   draw  the  bones  together,  but  they  cannot  push  them 
apart.     The  muscles  that  bend  the  wrist  or  the  ankle  can- 
not straighten  it  out  again.     But  nature  has  made  beautiful 
provision  for  this,  by  affixing  to  every  joint  two  or  more  sets 
of  muscles  for  the  various  kinds  and  directions  of  motion 
required.      Upon   the    hinge-joints  there  are  two  sets,  one 
to  bend,  the  other  to  straighten  them.     Thus  the  muscle  on 
the  front  of  the  upper  arm  bends  the  elbow,  and  the  muscle 
on  the  back  of  the  upper  arm,  straightens  it.     The  same  ar- 
rangement is  found  in  the  muscles  that  move  the  wrist,  the 
fingers,  the  knee,  the  ankle,  and  the  toes. 

629.  It  is  interesting  to  see  this  antagonism  of  muscles, 
and  their  alternate  working  in  the  movements  of  the  fingers. 
If  we  clasp  the  right  fore-arrn,  at  its  largest  part,  three  inches 
below  the  elbow,  with  the  fingers  and  thumb  of  the  left  hand, 
and  then  drum  rapidly  with  the  fingers  of  the  right  hand,  we 
shall   feel  the  swelling  and   decline  of  the  muscles  on  the 
opposite  sides  of  the  arm,  alternating  with  each  other,  and 
precisely   corresponding    with   the    motions   of  the   fingers. 
While  the  fingers  are  bending,  the  inside  muscles  swell  and 
the  outside   muscles  decline;    and,    while  the   fingers    are 
straightening,  the  outside  muscles  swell  and  the  inside  mus- 
cles  decline.      The  same    alternation    may  be   felt   in   the 
movements  of  any  other  joint. 

630.  The  hinge-joints  want  two  sets  of  muscles  only  — 
one  to  bend,  the  other  to  straighten      But  some  other  joints 


BONES,  MUSCEES,  EXERCISE  AND  REST. 


273 


are  not  limited  to  this  single  line  of  motion.  The  shoulder 
not  only  bends  forward  and  backward,  but  upward  and  down- 
ward ;  and  it  can  move  in  any  direction,  even  round  like  the 
spoke  of  a  wheel.  It  would  seem  necessary,  then,  that  there 
should  be  many  sets  of  muscles  to  produce  this  great  variety 
of  motions.  The  ball  and  socket  joints  are  supplied  with 

FIG.  LV.     Internal  Muscles  of  the  Back,  Shoulder,  and  Hip. 


a,  Muscle  that  lifts  the  shoulder- 
blade. 

6,  Raises  the  arm. 

c,  Rolls  the  arm  outward. 

d,  e,  Rhomboid  muscles,  draw 
the  shoulder-blade  upward. 


g, '  Serrafus,  attached  to  the 
back-bone  and  the  ribs,  draws 
the  ribs  down. 

h,  Straightens  the  hip  joint, 
and  rolls  the  thigh  outward. 


many  muscles,  (Fig.  LV.,)  which  act  individually,  succes- 
sively, or  in  combination,  and  produce  every  variety  of 
motion  ;  by  these  we  move  the  arm,  the  thigh,  the  wrist,  and 
the  thumb  in  any  direction  which  we  may  desire. 


274  PHYSIOLOGY    AND    HEALTH. 


CHAPTER  VII. 

Bones  are  Levers;  Muscles  are  moving  Powers. — Muscles  act  at 
Disadvantage.  —  Power  sacrificed  to  Convenience  of  Action.— 
Especially  in  the  Fingers  and  Toes.  —  Muscles  cooperate  to  pro- 
duce one  Motion.  —  Rapidity  and  Precision  of  Muscular  Action. 
—  Illustrated  by  Piano-Forte  Player.  —  Violinist.  —  Writing.  — 
Carpenter. 

631.  THOSE  muscles  which  are  situated  at  a  distance 
from  the  object  to  be  moved  work  at  great  disadvantage. 
If  that  muscle  which, bends  the  elbow  were  placed  in  the 
bend  of  this  joint,  and  its  lower  end  attached  to  the  lower 
end  of  the  fore-arm  (Fig.  LVI.  b)  instead  of  the  natural  posi- 
tion at  the  elbow,  it  would  act  with  more  power  than  it  now 

FIG.  LVI.     Upper  Arm  Biceps  misplaced. 


a,  b,  Biceps  attached  to  wrist. 

does.  But  muscles  so  situated  would  interfere  very  much 
with  the  freedom  of  the  movements,  and  with  the  application 
of  the  limbs  to  a  great  variety  of  purposes,  and  be  very 
awkward. 

632.  In  motion,  the  bones_are  levers,  a'hd  the  muscles 
are  the  moving  powers.  The  bones  of  the  fote-arm  are 
fixed  very  near  its  end,  to  the  extremity  of  the  bone  of  the 
upper  arm.  The  upper  bone  is  the  fulcrum  or  point  of 
support ;  the  muscles  that  move  this  lower  arm  are  at 
tached  to  it  within  less  than  half  an  inch  of  the  fulcrum, 
while  thp  whole  bone  or  lever  is  ten  to  twelve  inches  in 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  275 

length.    Consequently,  the  muscles  act  with  a  disadvantage 
of  twenty  or  twenty-four  to  one. 

633.  Nature   makes  sacrifice    of  power   to   convenience 
of  motion,  to  grace   of  structure,  and  to   beauty  of  limb. 
The  muscles  are  therefore  made  very  powerful.     When  we 
lift  a  pound  in  the  hand,  and  bring  the  fore-arm  to  a  hori- 
zontal position,  the  muscle  bending  the  arm  exerts  a  force 
which  would  lift  twenty  or  twenty-four  pounds,  if  it  were 
attached   to   the  point   where   the   weight   rests.     When   a 
strong  man  lifts  fifty  or  a  hundred  pounds  with  his  hands, 
holding  the  fore-arm  in  a  horizontal  position,  the   muscle 
that  raises  the  arm  exerts  a  force  equal  to  twenty  or  twenty- 
four  times  that  which  would  be  necessary  to  lift  the  same 
weight  if  it  were  fixed  directly  to  the  weight. 

634.  The  muscles   that  straighten  the  ankle,  and  raise 
the  body  upon  the  toes,   act  with  the  same  disadvantage 
upon  the  short  end  of  the  lever.     The  ankle  is  the  fulcrum, 
the  whole  foot  the  lever,  the  heel  the  short  arm,  and  the  foot 
in  front  of  the  ankle  is  the  long  arm.     It  is  plain  that  the 
power  required  to  move  the  foot  by  the  heel  must  be  as 
much  greater  than  that  which  could  move  it  by  the  toes  as 
the  anterior  part  of  the  foot  is  longer  than  the  heel,  which 
is  about  twelve  to  one. 

635.  Muscular   contraction    is    effected    with   rapidity  — 
in  some  cases,  almost  instantaneously.     This  is  seen  when 
the  musician  executes  rapid  pieces  of  music  on  his  flute; 
for  every  note   that  is    made  includes  two  motions  of  the 
muscles   on   the   fore-arm — one  to  lift,  and    the   other   to 
carry  down  the  fingers.     It  is  an  established  fact,  that  some 
persons  can  pronounce  distinctly  fifteen  hundred  letters  in 
a  minute.     The  pronunciation  of  every  one  of  these  .tetters 
must  require  a  distinct  and  double   action  of  the  muscles 
connected  with  the  voice  and  enunciation,  for  each  action 
includes  both  the  contraction  and  the  relaxation.     Here  are, 
therefore,  three  thousand  actions  in  one  minute.      Insects 
exceed  all  other  animals  in  the  rapidity  of  their  muscular 
motions.     It  is  calculated  that,  with  their  wings,  they  strike 


£76  PHYSIOLOGY    AND    HEALTH. 

the  air,  not  many  hundred,  but  even  many  thousand,  times 
a  second. 

636.  These  muscles  work  in  concert,  and  produce,  by 
their  cooperation,  just  the  motions  that  are  required.    It  is 
interesting  to  see  how  exact  is  this  harmony,  and  with  what 
precision  is  the  power  measured  from,  and  exertion  made 
by,  each  one  in  creating  any  motion.     We  lift  the  hand  to 
the  chin,  then  to  the  mouth,  then  to  the  nose,  to  the  eye, 
and  to  the  forehead.     In  each  of  these  motions,  there  is  a 
combination  of  several    or    many  muscular    actions ;    each 
muscle  and  each  fibre  pulls  just  so  much  as,  and  no  more 
than,  is  necessary  to  carry  the  hand  exactly  to  the  place 
appointed.     A  very   sjight  change  of  force  of  one  of  the 
muscles  in  the  shoulder  carries  the  hand  from  the  mouth 
to  the  nose,  and  from  the  nose  to  the  eye,  or  lets  it  fall  upon 
the  breast. 

637.  Performers   on  the   piano  strike    the  varied   notes 
with  equal  precision:  —  first  a,  then  b,  then  c  sharp,  then 
an  octave,  or  a  fifth,  or  a  third.     In  all  these  changes,  the 
hand  moves  half  an  inchr  quarter  of  an  inch,  four  inches 
and  one  half,  six  inches  and  a  quarter,  —  whatever  distance 
is  required,  it  moves  just  so  much  and  no  more, —  and  hits 
the  exact  note.     This  is  done  by  the  muscles  of  the  shoul- 
der,  elbow,   and   the   wrist,  —  all    in   harmonious   cooper- 
ation.     However  small    an   extent   of    contraction    of    the 
muscle   at    the   shoulder,    at   the   short   end   of   the   lever, 
is  needed  to  carry  the  hand  a  quarter  of  an  inch  to  the 
right  or  to  the  left,  just  that  extent,  that  hair-breadth  of 
contraction,  is  made,  —  no  more,  no  less,  —  and  the  unerr- 
ing finger  hits  the  note. 

638.  The  complete  government  of  the  muscular  action 
is  still  more  remarkably  manifested  in  the  skilful  violinist. 
He  determines  his  notes  by  touching  the  tip  of  his  finger 
on  the  strings.     If  he  touch  them  a  little  higher  or  a  little 
lowor,  he  varies  the  note.     The  most  accomplished  players 
acqaire  such  exact  control   and  discipline  of  the  muscles 
of  their  fingers,  that  they  can  produce  at  will  the  minutest 


BONES,     MUSCLES,     EXERCISE,     AND    REST.  277 

shades  of  difference  of  sound.  To  produce  the  precision 
of  motion  in  the  ends  of  the  fingers,  the  muscles  that  move 
them  must  contract  with  still  greater  precision,  without 
varying  a  fraction  from  the  required  amount  of  motion. 

639.  Another  illustration  will  present  itself  to  any 
one  when  he  is  writing.  He  moves  his  pen  through 
the  forms  of  his  letters  by  means  of  the  muscles  of  the 
thumb  and  fingers,  and  of  the  arm  and  shoulder.  These 
combine  their  actions,  and  carry  the  pen  now  up,  now 
down,  in  straight  or  curved  lines,  forward  and  backward. 
They  make  the  exact  contractions  that  are  needed.  The 
slightest  variations  of  these  contractions  make  an  e  in- 
stead of  an  t,  a  d  instead  of  an  a ;  yet  these  mistakes  are 
not  made,  but  the  letters  are  formed  in  the  exact  shape  that 
is  required. 

640  This  control  over  muscular  action  enables  the 
painter,  the  draughtsman,  and  the  engraver,  to  produce  the 
very  pictures  which  they  desire,  and  the  mechanic  to  use 
his  tools,  not  only  with  exactness,  but  with  safety  to  himself. 
When  a  carpenter  is  cutting  with  a  broad-axe,  upon  a  small 
block,  which  he  holds  with  his  left  hand,  he  strikes  boldly 
and  accurately.  But  a  very  slight  difference  of  the  con- 
traction of  the  muscles  of  the  shoulder  that  bring  the  upper 
arm  downward  and  forward  would  carry  the  axe  upon  the 
fingers,  and  not  upon  his  block.  When  driving  nails,  he 
holds  the  nail  between  the  thumb  and  finger  of  the  left 
hand,  while  he  lifts  the  hammer  with  the  right.  He  hits 
the  nail  upon  the  head ;  and  yet  how  exceedingly  small  a 
variation  of  the  muscular  contraction  would  carry  the  ham- 
mer upon  the  thumb  or  the  finger,  and  not  upon  the  nail ! 
24 


278  PHYSIOLOGY    AND    HEALTH. 


CHAPTER   VIII. 

Strength  of  Muscles  not  always  dependent  on  Size.  —  Strength  differs 
in  various  Animals,  in  Man  and  Insects,  and  in  various  Men. 
—  Exercise  of  Muscles  increases  their  Size  and  Power.  —  Muscles 
in  Limbs  that  are  exercised  stronger  than  those  that  are  not  used. 

641.  Muscles   are,   in   general,   strong   in  proportion    to 
tkeir  size ;  but  this  is  not  a  univcrsal^law.     Birds  are  very 
strong,  but  they  have  not  very  large  muscles.     These  would 
add  to  their  weight,  and  be  very  inconvenient  for  flight.     On 
the  contrary,  fishes  have  large  muscles,  yet  are  not  very 
strong.     Living  in  the  water  as  they  do,  which  is  nearly  as 
heavy  as  themselves,  great  bulk  is  no  impediment.     They 
move  about  as  well  with  a  large  as  with   a  small  mass  of 
flesh. 

642.  The   difference   of    muscular    power    in    different 
classes  may  be   shown    by    comparing  man   with  some  in- 
sects.    A  man  must  be  more  than  usually  active  to  be  able 
to  jump  his  own  height.     A  man  of  ordinary  strength  can 
hardly  lift  more  than  twice  his  own  weight ;    one  of  the 
strongest  men  on  record  could  lift  eight  hundred  pounds. 
But  insects  have  astonishing  strength  of  muscle.     A  flea  will 
leap  sixty  times  its  own  length,  and  one  of  the  beetles  can 
support  uninjured,  and  even  elevate  a  weight  equal  to  five 
hundred  times  that  of  its  own  body.     If  a  man  were  strong 
and   active  in  the  same  proportion,  he  could   jump  three 
hundred  and  forty  feet,  or  more  than  twenty  rods,  and  lift 
aoout  three  and  a  half  tons""  weight. 

643.  Among  animals  of  the  same  kind,  especially  among 
men,  it  may  be  safely  considered  that  the  muscular  power 
corresponds  with  the  size  of  the  muscles.     Though  all  men 
are  endowed  with  the  same  muscles,  and  these  "are  arranged 
in  the  same  manner  in  all,  yet  it  is  manifest  that  aH  men  are 
not  equally  strong,  and  that  their  strength  is  not  distributed 
in  the  same  proportion  over  the  various  parts  of  the  body. 


BONES,  MUSCLES,  EXERCISE,  AND  REST.     279 

One  man  is  very  powerful,  another  is  very  weak ;  one  is  strong 
in  the  arms  and  weak  in  the  legs,  while  another  is  strong  in 
the  legs  and  weak  in  the  arms. 

644.  This  great  and  almost  infinitely  varied  muscular 
power  is  given  to  men  and  animals  for  action.  It  was  no 
intention  of  the  benevolent  Creator  that  this  should  remain 
dormant.  Some  of  the  involuntary  muscles  work  inces- 
santly; day  and  night,  asleep  or  awake,  from  birth  to 
extreme  old  age,  the  heart  beats,  and  the  chest  moves,  and 
the  digestive  organs  carry  on  their  operations  and  find  no 
rest ;  nor  yet  are  the  muscles  which  perform  these  labors 
exhausted  or  even  weary.  It  is  the  design  of  our  being  that 
we  use  the  muscles  that  are  put  under  our  control,  and,  by 
their  action,  both  procure  our  subsistence  and  sustain  our 
health.  These  two  ends  are  attainable  b*y  the  same  means, 
and  are  made  to  correspond  with  each  other. 

645.  Exercise  of  tJie  muscles  increases  the  waste  of  their 
dead  particles ,  (§  252,  p.  115,)  and  consequently  the  demand 
for  nutrition.     The  arteries  then  act  more  vigorously,  carry 
more  blood,  and  deposit  more  new  particles.     The    active 
muscle,    being   better   nourished,    is    composed   of    fresher 
atoms,  and  has  more  strength.     When  this  exercise  is  ju- 
diciously taken,  neither  too  little  nor  too  much,  the  nutrition 
exceeds  the  absorption,  more  new  atoms  are  brought  .than 
old  carried  away ;  then  the  muscle  grows  larger,  and  more 
dense  and  powerful.     We  find  proof  and  examples  of  this 
too  frequently  to  escape  notice.     The  muscles  of  the  inac- 
tive, those  who  neither  labor  nor  exercise,  are  small,  soft, 
and  flabby,  and  hang  loosely  on  the  bones ;  consequently, 
they  are  weak.     But  the  muscles  of  the  active  and  laborious 
are  large  and  firm ;  they  are  full  and  very  strong,  and  en- 
dowed with  great  energy  of  action. 

646.  The  robust  and  healthy  laborer  exercises  his  limbs 
and  his  trunk,  and  consequently  has  strong  muscles.     He 
can  take  his  scythe  and  mow  from  morning  till  night,  and 
follow  this  from   Monday  till  Saturday;    he  can  lay  stone 
wall  or  cut  wood  with  the  same  perseverance;  and  he  does 


280  PHYSIOLOGY    AND    HEALTH. 

all  this  without  any  great  fatigue.  But  let  a  student,  whose 
arms  are  unaccustomed  to  labor,  and  whose  muscles  are 
therefore  soft,  small,  and  feeble,  undertake  to  do  either,  and 
he  will,  in  a  few  minutes,  be  exhausted. 

647.  The  student  is  not  necessarily  weak  in  body.     If  he 
is  faithful  to  the  laws  of  health,  and  takes  daily  exercise   to 
a  suitable   degree,  his  muscular  system  is  sufficiently  de- 
veloped, and  he  is  strong  enough  for  the  support  of  health, 
though  he  may  be  much  weaker  than  the  farmer.     He  can 
walk  several  miles.     He  can  do  the  work  of  gardening,  rake 
hay,  or  perform  the  lighter  labor  of  farming  for  an  hour  or 
two,  without  much  fatigue.     The  muscles  of  the  inactive 
and  indulged  girl,  who  has  been  taught  that  exercise  —  how- 
ever useful  to  the  laborer,  and  proper  for  men  and  boys  —  is 
not  requisite  for  her  delicate  frame,  are  soft,  like  those  of  a 
babe,  and  not  much  stronger.     If  she  attempts  to  walk  a  mile, 
she  will  fail  of  accomplishing  her  purpose,  or  suffer  from 
fatigue,  perhaps  from  exhaustion. 

648.  Exercise  develops  the  form  and  the  strength  of  the 
muscles  which  are  called"  into  operation.     In  order  that  the 
whole  should  be  developed  and  strengthened,  this  exercise 
should  be  so    varied   as   to  use  every  one  of  them.     The 
farmer  is  at  one  time  cutting  wood,  and  thereby  using  the 
muscles  of  the  arms  and  shoulders ;  at  another,  laying  stone 
wall,  wjth  the  muscles  of  his  arms,  shoulders,  and  back;  at 
another  time,  he  is  ploughing,  and  using  the  muscles  of  his 
arms,  back,  and  legs;    sometimes  pulling,  sometimes  push- 
ing, lifting,  striking,  treading;  and  in  all  these  ways  calling 
every  muscle  into  action.     His  muscular  energies  are,  con- 
sequently, universally  developed,  and  he  is  strong  in  all  his 
frame  beyond  other  men.     There  are  other  occupations  that 
have  nearly  the  same  effect,  but  none  that  give  the  variety 
of  exercise  and  universality  of  muscular  power  that  comes 
from  the  cultivation  of  the  earth. 

649.  All  employments  that  call  for  the  use  of  only  a  part 
of  the  muscles,  but  not  the  whole,  develop  the  size  and  the 
strength  of  those  that  are  used  more  than  the  others.     So 


BONES,    MUSCLES,    EXERuISE,    AND    REST.  281 

we  find  some  men  are  very  strong  in  some  of  their  limbs, 
and  weak  in  others ;  and  these  strong  and  weak  parts  differ 
according  to  the  habits  and  employments  of  the  people.  A 
sailor  uses  his  arms  more  than  his  legs.  He  pulls  ropes, 
and  lifts  the  anchor,  but  has  little  opportunity  of  walking. 
Consequently,  the  muscles  of  his  arms  and  shoulders  are/ 
large,  strong,  and  hard,  while  his  legs  are  smaller  and 
weaker  than  those  of  other  men.  The  blacksmith  uses  the 
same  muscles,  and  has  the  same  muscular  development  of 
his  arms,  and  comparative  weakness  of  his  legs.  The  pe- 
destrian and  the  dancer  have  large  and  strong  muscles  of 
the  lower  limbs,  while  their  arms  are  comparatively  small 
and  feeble. 

A  similar  difference  of  muscular  development  is  manifested 
in  the  porter.  His  employment  calls  fof'the  exercise  of  the 
muscles  of  the  back  more  than  that  of  other  men.  He  car- 
ries his  burdens  on  his  head  or  his  shoulders.  It  is  necessary, 
therefore,  for  him  to  keep  his  spine  erect  by  the  constant  and 
vigorous  action  of  the  muscles  of  that  region.  They,  there- 
fore, are  used  more,  and  grow  larger  and  stronger,  than  the 
spinal  muscles  of  men  who  are  otherwise  occupied. 

This  law  of  special  muscular  development  from  special  use 
affects  the  lower  animals  as  well  as  men.  Hence  we  find  in 
them  a  growth  and  an  increase  of  power  in  the  muscles  that 
are  used,  and  a  comparative  smallness  and  weakness  in  those 
that  are  not  used.  The  wild  birds  use  their  wings  mostly  for 
locomotion.  They  sustain  themselves  very  long  in  the  air, 
and  fly  great  distances.  They  have,  therefore,  very  large  and 
strong  muscles  on  their  breasts  and  wings.  And,  as  they 
walk  but  little,  the  muscles  of  their  legs  are  comparatively 
small  and  weak. 

But  the  domestic  fowls  seldom  fly;  they  use  their  legs 
mostly  for  locomotion.  They  have,  therefore,  much  smaller 
muscles  on  their  breasts  and  wings,  and  much  larger  on  their 
legs.  This  difference  is,  perhaps,  the  most  remarkably  seen 
in  the  wild  and  domestic  turkeys  and  geese. 
24* 


282  PHYSIOLOGY    AND    HEALTH. 


CHAPTER   LX. 

Some  Muscles  strong  and  others  weak  in  the  same  Person.  —  Ameri- 
can Women  walk  little.  —  Muscles  become  weak  by  Disuse.  — 
Whole  System  made  stronger  and  more  lively  by  muscular  Exer- 
cise. This  aids  Digestion,  Respiration,  Circulation,  and  increases 
animal  Heat. 

650.  THE  muscles  being  thus  unequally  used,  and  their 
strength  unequally  developed,  in  the  same  person,  he  may 
then  be  very  strong  in  one  part,  and  weak  in  another.     The 
sailor  or  the  blacksmith  would  be  wearied  with  a  walk  of  a 
few  miles,  while  the  pedestrian  might  not  be  able  to  carry 
the  porter's  burden,  and  the  porter  would  soon  be  exhausted 
with  swinging  the  scythe  or  the  sledge-hammer. 

651.  Many  women,  however  industrious  at  home,  are  not 
generally  accustomed  to  much  exercise  abroad.     Their  mus- 
cles of  locomotion,  being  little  used,  are  neither  large  noi 
strong.     They  cannot  move  with  a  vigorous  gait  nor  with  an 
elastic  step.     They  walk  %vith  so  little  ease  and  energy,  and 
are  so  soon  fatigued,  that  they  find  very  little  inducement  to 
go  any  considerable  distance  on  foot.     Many  who  can  spin 
and  weave,  wash,  make  butter  and  cheese,  and  perform  all 
sorts  of  even  the  hardest  household  labors,  without  any  great 
weariness,  are  overcorne  by  a  short  walk. 

An  example  of  this  was  found  in  an  unusually  industri- 
ous aird  healthy  wife  of  a  farmer,  in  a  country  town  of 
Massachusetts.  Few  women  were  more  faithful  and  ener- 
getic in  the  management  and  labor  of  the  house.  Nothing 
was  too  hard  for  her  strength,  no  household  work  was  too 
great  for  her  energy  ;  all  the  domestic  avocations,  in  their 
due  course,  were  her  ordinary  exercise.  But  she  never 
walked  abroad.  She  lived  about  a  mile  from  the  village 
and  the  church,  and  went  to  these  very  frequently,  on  busi- 
ness or  pleasure,  and  for  worship.  But  she  had  always  a 
horse  and  chaise  at  command,  and  always  rode.  In  her 


BONES,    MUSCLES,    EXERCISE,    AND    BEST.  283 

later  years  she  said  that,  for  near  forty  years,  she  had  not 
walked  from  her  house  to  the  village,  and  she  thought  she 
had  not  strength  to  do  it. 

652.  The  strength  and  size  which  the  muscles  gain  by 
exercise  are  to  be  preserved  by  the  same  means.     If  suffered 
to  remain  inactive,  they  lose  their  fulness  and  power,  they 
shrivel,  and  become  soft  and  feeble.     Whatever  may  be  the 
cause  of  the  disuse  of  the  limbs,  these  consequences  of  waste 
and  weakness  must  follow.     An  active  and  strong  man  re- 
ceives an  injury,  perhaps  a  cut  on  the  foot.     This  wound, 
without  producing  any  general  disease,  may  lay  him  up,  and 
keep    him    still    for   some    months.      When    his    wound   is 
healed,  he  finds  his  legs  are  weak,  and  unable  to  do  their 
former  labor. 

653.  Dr.  Reid  cut  the  great  nerve  that  went  to  one  of 
the  legs  of  a  rabbit.     The  limb  was  immediately  palsied,  and 
could  not  move.     In  seven  weeks  he  killed  the  animal,  and 
compared  the  muscles  of  the  palsied  leg  with  those  of  the 
opposite    and    sound   one.     They    were    paler,    softer,    and 
smaller,  and  weighed  only  about  half  as  much  as  those  of 
the  other  limb.     The  bones,  also,  of  the  inactive  leg  were 
diminished  in  size.     So  the  muscles  of  the  paralytic  man, 
who  does  not  and  cannot  walk,  become  shrivelled  and  weak. 
Mr.  J.,  in  consequence  of  an  injury,  has  not  been  -able  to 
bend  the  foot  on  the  leg. for  more  than  sixteen  years.     The 
muscles  which  formerly  lifted  his  foot,  not  having  been  used 
for  so  long   a  time,   are  now  shrivelled,  and  much  smaller 
than  in  other  men  of  his  size. 

654.  Exercise  not  only  invigorates  its  own  apparatus  of 
motion,  but  it  contributes  to  the  strengthening  of  all  the 
other  systems,   and  aids  them  in  the  performance  of  their 
functions.     The  man  of  active  habits  of  body  has  a  better 
appetite  and  digestion  and  is  better  nourished,  he  breathes 
more  freely,  he  has   a  freer  circulation  of  the  blood  and  a 
clearer  brain,  than  the  inactive  and  the  sluggish.     The  la- 
borer, the  farmer,  the  active  mechanic,  and  sailor,  seldom 
complain  of  want  of  appetite  or  of  indigestion.     They  work 


284  PHYSIOLOGY  AND  HEALTH. 

hard  and  eat  heartily.  Their  food  gives  them  a  comfortable 
sensation,  and  they  are  well  nourished.  But  the  student, 
the  clerk,  the  'watchmaker,  the  engraver,  all  men  engaged 
in  sedentary  employments,  and  men  and  women  of  no 
occupation,  often  complain  of  failing  appetite  and  weak 
digestion.  If  they  eat  heartily,  they  feel  now  and  then  dis- 
tressed after  so  doing,  and  give  painful  evidence  that  if  a 
man  do  not  work,  he  cannot  eat  satisfactorily.  The  food  the 
inactive  man  eats  gives  him  neither  the  nourishment,  nor 
the  elastic  energy,  nor  the  pleasurable  sensations,  that  it  does 
to  the  man  of  more  active  habits. 

655.  So  closely  is  use  of  the  muscular  system  connected 
with  appetite  and  digestion,  that  exercise  is  usually  one  of 
the  first  means  advised  for  their  restoration  when  they  are 
impaired ;  and  thus  we  see  dyspeptic  students  leaving  col- 
lege, and    dyspeptic    sedentary  men    giving    up  their  busi- 
ness, and  betaking  themselves  to  travelling,  to  farming,  or 
some  other  active  employment,  as  the  best  method  of  regain- 
ing their  lost  health.     But  if  the  amount  of  exercise  which 
the  invalid  takes  as  a  means  of  recovery  had  been  distributed 
through  his  previous  days,  and  mingled  with  the  hours  of 
study  and  sedentary  occupation,  very  probably  it  would  have 
saved  him  from  his  present  suffering  and  indigestion. 

656.  When  we  run,  or  walk,  or  labor  in  any  way,   the 
heart  beats   more  rapidly  than   when  we  are  at  rest.     The 
blood  is  carried,  not  only   more  frequently,    but  in  larger 
quantities,  through  the  muscular  system,  and   through  the 
whole  frame.     The  alternate  swelling   and   decline  of  the 
muscles,  in  their  contraction  and  relaxation,  press  upon  the 
veins,  and  force  the  blood  out  of  them;  and,  as  the  valves  in 
the  veins  do  not  permit  this  blood  to  go  backward,  it  must 
go  onward  toward  the  heart.     This  is  especially  seen  in  the 
process  of  bleeding  from  the  arm,  when  the  patient  holds  a 
cane  or  ball  in  his  hand,  upon  which  he  presses   and   re- 
laxes his  fingers  in  rapid  succession.     This  action  swells  the 
muscles  on  the  arm,  the  swelling  presses  upon  the.  veins,  and 
forces  the  blood  onward  and  outward  through  the  aperture. 


BONES,    MUSCLES,     EXERCISE,     AND    REST.  285 

All  exercise  of  the  muscles  directly  aids  the  circulation  in 
the  veins,  and  indirectly  hastens  it  in  the  heart  and  arteries. 

657.  When  we  walk,  we  breathe  more  rapidly  than  when 
sitting  still   (§  342,  p.  150.)     If  we  run,  or  labor  with  great 
violence,  we  breathe  very  rapidly.     During  the  process  of 
exercise,  more  fresh  blood  is  carried  in  the  arteries  to  the 
organs,  especially  the  muscles,  and  the  more  impure  blood 
is  brought  away  in  the  veins.     The  changes  of  living  and 
dead  particles  are  more  rapid.  (§252,  p.  115.)     There  is 
then  a  greater   quantity  of  old  and  dead  particles  —  more 
carbon  and  hydrogen  —  to  be  carried  out  of  the  system,  and 
consequently  a  greater  demand  for  oxygen  to  convert  these 
into  carbonic  acid  gas  and   water.     For  this  purpose   the 
chest  expands,  and  we  breathe  more  frequently,  and  give  the 
lungs  the  increased  quantity  of  air  that  is  needed.     Hence 
we  see  that  exercise  aids  respiration,   and  is  most  advan- 
tageously taken  in  the  fresh  air  abroad. 

658.  When  a  boy  is  cold  in  the  winter,  he  runs  to  get 
himself  warm ;  when  a  passenger  is  insufficiently  warm  in 
his  vehicle,  he  gets  out  and  walks  or  runs  by  the  side  of  his 
horse  to  warm  himself.     When  a  farmer  sits  in  his  house  in 
a  cold  day,  he  has  a  large  fire,  sufficient  to  heat  the  room 
to  near  70°,  in  order  to  keep  himself  comfortable.     If  he 
ride  at  the  same  season,  he  wears  a  great  coat,  and  wraps  a 
buffalo  robe   about  him.     But,  when  he  takes  his  axe  and 
cuts  his  wood  in  the  open    air,  he   wants  neithet  fire  nor 
great  coat,  perhaps  not  even  his  close  coat.     His  exercise 
keeps  him  warm,  and,  if  he  labors  violently  in  loading  his 
sled  or  his  wagon  with  heavy  logs,  he  becomes  uncomfortably 
hot,  and  may  get  into  a  free   perspiration.     The   muscular 
action  increases   the   amount  of  wasted  atoms  to  be  con- 
sumed   in    the   body,  and   the   more  rapid   respiration  and 
circulation  increase   the  fuel   and  oxygen  for   the   internal 
fire,  which  burns  more  and  more  in  proportion   to  the  ac- 
tivity and  violence  of  the  labor.    (§  422,  p.  181.) 


286  PHYSIOLOGY    AND    HEALTH. 


CHAPTER    X. 

Muscular  Action  strengthens  the  whole  System,  and  aids  the  Brain 
and  Mind.  —  Neglect  of  Exercise  debilitates  the  whole  Powers  — 
Various  Persons  need  different  Quantities  of  Exercise.  —  Too  vio- 
lent Exercise  exhausts. 

659.  IT  will  be  easy  now  to  understand  how  a  muscle 
that  is  used  grows    and  becomes   hard    and   strong.     The 
active  contraction  promotes  the  flow  of  blood  and  increases 
nutrition  by  the  deposit  of  new  particles  of  flesh.     After  the 
labor  has  ceased,  there  is  less  waste  of  particles  by  the  absorp- 
tion of  the  old.     But  the  rapid  motion  of  the  heart  does  not 
cease  with  the  exercise ;  the  increased  flow  of  blood  is  thus 
continued,  and  with  it  the  increased  deposit  of  new  particles 
in  the  muscles;    and  thus  it  gains  in  size  and  strength  by 
labor. 

660.  Thus  we  see  that  muscular  action  promotes  diges- 
tion, respiration,  circulation,  and  nutrition,  and  it  assists  the 
preparation  and  maintenance  of  animal  heat.    Finally,  as  the 
health  and  functions  of  the  nervous  system   are  connected 
with  the  condition  of  the  other  systems,  we  may  safely  add, 
that  muscular  exercise  aids  the  brain  also  in  its  work,  and 
that  no  mind  can  be  the  clearest  and  the  most  vigorous  for 
study  and  reflection,  unless  the  body  is  accustomed  to  action. 

661.  A  sagacious   physician,   whose    domestic    economy 
was  worthy  of  all  imitation,  when  any  one  of  his  daughters 
complained  of  a  headache,  was  accustomed  to  inquire,  first, 
whether    she   had    taken  her  usual   exercise  abroad ;    and, 
if  this  had  been  insufficient  for  the  purpose,  he  frequently 
advised,  not.  medicine,  but  another  walk.     Some  judicious 
schoolmasters,  when  they  find  their  boys  and  girls  heavy  and 
indisposed  to  study,  send  them  out  to  play  awhile.     After 
exercise  out  of  doors,  they  return  to  their  studies  with  new 
alacrity.     If  older  students,  when  they  find  it  difficult  to  fix 
their  minds  upon  the  subjects  before  them,  —  when  the  reason- 
ing powers  are  clouded  and  the  imagination  is  dull,  —  would 


• 


BONES,    MUSCLES,    EXEECISE,    AND   REST.  287 

leave  their  books  and  their  studies,  and  walk,  or  otherwise 
use  their  muscles  abroad,  they  might  recover  that  energy 
of  brain  and  mental  clearness  which  they  had  struggled 
without  success  to  gain  while  they  were  in  their  rooms. 

662.  A  few  years  ago  an  unusually  robust  youth  left  his 
home  in  the  country,  and  went  to  college.  He  was  of  a 
quiet,  contemplative  disposition,  very  fond  of  his  books,  and 
faithful  to  his  plans  of  life.  He  did  not  enter  into  the 
active  sports  of  the  other  students;  and  the  walks  in  the 
neighborhood  of  the  college  did  not  interest  him.  Yet  he 
was  then  in  excellent  health,  had  a  good  appetite,  and  ate 
heartily.  Moreover,  he  was  an  industrious  student,  and  a 
good  scholar.  While  the  first  year  wore  away,  he  walked 
little,  studied  assiduously,  and,  at  the  end,  nis  health  was  still 
good.  The  second  year  found  him  and  left  him  about  the 
same,  except  that  he  walked  rather  less.  He  was  advised  to 
pursue  a  different  course,  and  the  necessity  of  muscular 
action  was  urged  upon  him  as  a  law  of  health.  He  ac- 
knowledged the  law  in  general  terms,  but  claimed  to  be  an 
exception  to  its  requirements.  He  had  lived  two  years  with 
very  little  exercise,  and  yet  he  was  not  only  well,  but  was 
able  to  study  as  much  as  his  fellows ;  he  therefore  supposed 
that  he  was  exempted  from  the  almost  universal  necessity  of 
action  abroad.  His  third  and  fourth  years  passed  away,  in 
much  the  same  manner,  except  that  he  walked  less  and  less, 
for  the  reason  that  it  was  more  and  more  irksome  to  him ; 
but  his  health  was  not  very  perceptibly  deteriorated.  After 
he  left  college,  he  taught  school  one  year,  and  then  com- 
menced the  study  of  his  profession,  and  pursued  this  about 
two  years,  with  the  same  habit  of  physical  inaction  and 
mental  industry.  But  in  this  period  his  appetite  began  to 
fail,  and  he  suffered  from  indigestion.  His  powers  of  mind 
languished,  and  his  spirits  grew  dull.  He  lost  his  power  of 
application  and  habitual  cheerfulness.  At  the  end  of  this 
period  he  broke  down,  and  was  unable  to  pursue  his  pro- 
fessional studies  any  longer;  he  then  gave  them  up,  and 
went  to  his  home  a  confirmed  dyspeptic.  There  he  re- 


288  PHYSIOLOGY    AND    HEALTH. 

mained  several  years  an  invalid,  incapable  of  any  business, 
or  of  engaging  in  any  more  study.  That  firm  and  inflexible 
constitution,  which  had  held  out  seven  years  against  the  vio- 
lation of  the  physical  law,  was  equally  inflexible  with  regard 
to  recovery,  and  required  more  than  seven  years  to  be  so  far 
restored  as  to  allow  him  again  to  engage  in  any  pursuit. 

663.  The  same  quantity  of  exercise  is  not  necessary  for 
the  health  of  all  men  and  women,  nor  are  all  able  to  endure 
the  same  amount  of  labor.     It  must  be  measured  out  accord- 
ing to  the  constitution,  the  strength,  and  the  habits  of  various 
persons.      What  is  necessary  for  one  may  exhaust  another. 
The  quantity  of  action  should  be  determined,  not  by  any 
previously  established  theory,  but  by  its  results  in  each  case 
—  by  its  effects  upon  each  individual. 

664.  If  the  exercise  is  too  violent  or  too  long  continued, 
the  body  is  rather  exhausted  than  invigorated;  the  process 
of  waste  is  carried  on  beyond  the  power  of  nutrition,  and 
then  the  muscles  grow  thin  and  lank,   rather  than  full  and 
strong,  and  the  individual  suffers  from  languor,  and  is  ill 
fitted  for  any  other  labor.     But  if,  on  the  other  hand,  after 
the  exertion,  we  are  only  a  little  fatigued,  but  not  languid,  — 
if  we  are  ready  then  for  any  other  occupation,  for  reading, 
writing,  or  conversation,  —  we  may  be  assured  that  the  in- 
creased waste  is  counterbalanced  by  the  increased  nutrition, 
and  the  labor  has  strengthened   rather   than  weakened  the 
body.     The  exercise  should  never  go  beyond  a  slight  fa- 
tigue, never  to   exhaustion,    nor  produce  that    uneasy  rest- 
lessness which  unfits  one  for  any  other  immediate  duty,  and 
which  rather  wears  uoon  than  adds  to  the  general  health. 

665.  Although  tne  muscles  have  a  power  of  contraction, 
they  have  not  a  permanence  of  this   power.     The  muscle 
needs  alternate  relaxation  with  its  labor.     One  can  strike  with 
more  force  than  he  can  pull,  and  lift  a  much  heavier  weight 
than  he  can  continue  to  hold  up,  for  even  a  few  minutes.     It  is 
one  of  the  severest  and  most  painful  punishments  to  compel  a 
boy  in  school  to  hold  out  the  arm  in  a  horizontal  position, 
even  without  a  weight  in  his  hand,  for  any  length  of  time. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  289 


CHAPTER  XI. 

Feeble  Persons  weakened  by  any  Excess  of  Exercise,  but  strength- 
ened by  very  moderate  Exertions.  —  Exercise  must  be  adapted 
exactly  to  the  Strength.  —  In  this  Manner  Strength  may  be  in- 
creased daily.  — 1{  is  an  Error  fo*  dyspeptic  Students  or  Invalids 
of  the  City  to  attempt  to  be  Farmers  or  Sailors. —  Gymnasium  not 
adapted  to  Powers  of  th«(se  who  use  it. 

666.  WE  are  told  by  some  that  they  cannot  walk  or  move 
in  any  way  abroad,  that  it  always  gives  them  the  headache  or 
pain  in  the  limbs,  and  that  they  return  from  their  excursions 
sick  and  languid.     This  is,  indeed,  a  truth;  but  it  is  very 
easily  explained.     These  uncomfortable  consequences  flow, 
riot  from  the  mere  exercise,  but  its  excess.     The  walk  which 
exhausted  them  may  have  been  short  compared  with  those 
which  others  take  with  ease,  and  return  from  with  buoyant 
alacrity ;  but  it  was  too  much  for  their  feeble  and  unpractised 
limbs.     But,  although  a  mile  exhausts,  half  a  mile  will  prob- 
ably cause  merely  fatigue,  and  ultimately  strengthen ;  and,  if 
this  be  too  much,  a  still  shorter  one  will  answer  the  desired 
purpose. 

667.  If  the  exercise  be  judiciously  begun,  with  just  the 
quantity  that  is  sufficient,  and  no  more,  it  will  leave  the  per- 
son in  slight  fatigue ;  but  in  a  little  while,  he  will  feel  more 
fresh  and  vigorous,  and   capable  of  making  a   still  greater 
exertion.     Adopting  this  method,  the  feeble  must  begin  ac- 
cording to  the  degree  of  his  strength,  however  small ;  and 
with  proper  management  and  perseverance,  he  may  go  on 
adding  a  little    exertion  day  by  day,  and  accomplish  more 
and  more. 

668.  However  small  may  be  the  person's  strength,  that 
must  be  the  measure  of  the  exertion.     However   low  the 
power,  that  must  be  the  starting-point.     Any  other  measure- 
ment, any  other  point  of  beginning,  would  be  fatal  to  the 
hopes  of  gaining  strength  by  the  effort. 

A   young    man,   in   Waltham,    Massachusetts,   was    very 
25 


290  PHYSIOLOGY    AND    HEALTH. 

feeble,  bat  not  sick.  Pie  was  advised  by  his  physician  to  set 
out  upon  a  journey  on  foot,  but  was  cautioned  not  to  walk 
at  any  time  until  exhausted.  He  began  his  journey  in  the 
morning,  and,  with  short  exertions  and  frequent  rest,  he 
walked  three  miles  on  the  first  day,  and  was  fatigued.  The 
next  morning,  to  his  surprise,  he  felt  more  vigo.r  and  courage 
to  go  on,  and  started  again.  He  walked  on  that  day,  in  the 
same  manner,  and  accomplished  four  miles  before  night. 
He  thus  gained  strength  and  energy,  day  by  day,  adding  little 
to  little,  and  finally  walked  to  Niagara  Falls  —  more  than 
five  hundred  miles.  After  viewing  these  to  his  satisfaction, 
he  returned,  in  a  much  shorter  time  than  he  went.  But  he 
did  not  return  by  a  direct  course.  He  visited  the  interesting 
places  in  the  neighborhood  of  his  homeward  route,  and  at 
the  end  of  his  sixth  week,  he  reached  home,  having  walked 
more  than  a  thousand  miles  in  forty-two  days.  On  the  last 
day  he  had  walked  forty  miles,  and  was  so  little  fatigued 
with  the  day's  journey,  that  in  the  evening  he  felt  sufficient 
energy  to  visit  his  young  friends  in  the  neighborhood. 

669  There  is  a  common  notion,  that,  as  great  action 
gives .  strength  to  the  strong,  it  will  do  the  same  for  the 
weak;  therefore  the  debilitated  student  and  the  languid  child 
of  the  city,  who  have  become  so  feeble  as  to  be  unable  to 
carry  on  their  studies  or  attend  to  their  sedentary  business 
in  the  counting-room,  are  advised  to  leave  their  occupations, 
andxgo  into  the  country,  and  work  with  the  farmers.  They 
commence  their  labors  with  zealous  courage;  but  they  soon 
give  up.  They  find  that  they  are  exhausted  by  the  work, 
which  the  practised  laborer  accomplishes  without  apparent 
exertion  or  fatigue.  Instead  of  being  invigorated,  they  are 
weakened,  and  they  abandon  too  frequently  all  hope  of 
recruiting  their  wasted  powers  by  muscular  exercise.  But 
if,  instead  of  attempting  to  mow,  plough,  or  dig,  for  several 
hours  in  succession,  they  undertake  the  lightest  work,  and 
do  this  for  a  few  minutes  or  an  hour  or  two,  with  fre- 
quent, and  perhaps  long  intervals  of  rest,  they  gain  power 
HS  the  pedestrian  just  now  described. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  291 

670.  For  the  same  purpose,  and  with  the  same  mistake 
of  means  and  ends,  young  men  in  ill  health  are  sometimes 
sent  to  sea  as  sailors,  and  engage  to  do  the  work  of  the  com- 
mon and  practised  seamen.     They  err  in  their  estimate  of 
the  effect  of  hard  labor  on  the  weakened  frame,  and  are 
obliged  to  give  up  their  purpose  or  alter  their  plans.     But 
a  much    better    and   more   successful    method   is,  to  enlist 
as  weak  sailors,  without  wages,  and  without  responsibility. 
This  allows  them  to  work  only  so  much  as  their  strength 
gains  upon  them  ;  and,  if  this  be  judiciously  expended,  they 
will  add  to  it  daily,  and   accomplish  all  they   desire,  and 
return,  after  some  months,  in  more  vigorous  health. 

671.  It  was  supposed,  several  years  ago,  that  the  gym- 
nasium would  furnish  opportunities  and  inducements  to  ex- 
ercise for  all  such  as  were  not  required,  by  their  business 
or  their  condition  in  life,  to  labor.     In  these  establishments 
means  were  provided  for  using  all  the  limbs  and  muscles. 
There  were  ropes  to  climb,  parallel  bars  to  walk  upon  with 
the  hands,  and  wooden  horses  to  mount  upon  or  leap  over. 
There  were  means  for  climbing,  swinging  upon  the  arms, 
leaping,  vaulting,  and  for  performing  some  of  the  feats  of 
the  rope-dancer,  and  some  of  the  labors  of  the  sailor.     These 
exercises   were   active,    and   even    laborious.      Those    who 
engaged  in   them  made,  or  endeavored  to  make,  the  exer- 
tions which  only  strong  men  could  make.     But  they  were 
soon  fatigued,  and  left  the  gymnasium ;  or,   if  they  perse- 
vered, were  nearly  exhausted.     The  error  was  in  not  adapt- 
ing the  mode  to,  and  measuring  the  amount  of  exertion  by, 
the  strength  of  those  who  needed  it.     The  students  of  Cam- 
bridge, in  1826,  (§  165,  p.  78,)  complained  that  they  were 
fatigued,  and  sometimes  overcome,  rather  than  invigorated, 
at  the  gymnasium,  and  were  unfit  for  study  for  some  hours 
afterwards.      The  final  result  of  this   attempt  to  introduce 
this   system    of  exercises   into   our    colleges,    schools,    and 
cities,  was  a  general  failure.     But,  if  they  had  been  arranged 
and  measured  so  as  to  correspond  with  the  little  strength  of 
sedentary  men,  they  might  have  still  been  in  general  use, 
and  productive  of  great  advantage  to  health. 


292  PHYSIOLOGY   AND    HEALTH. 


CHAPTER  XII. 

Kinds  of  Exercise.  —  Walking.  —  Sports  of  Childhood  allowed  to  and 
beneficial  to  Boys. —  Girls  exercise  more  quietly,  and  with  less 
Advantage.  —  English  and  American  Women.  —  Exercise  of  the 

Arms   and    Chest.  —  Carpenters'    Tools.  —  Time   for  Exercise. 

Morning  and  Evening  not  the  best. 

672.  There  are  as  many  varieties  of  exercise  as  there 
are  muscles  in  the  human  body.  It  is  not  easy  to  determine 
which  of  these  is  the  best,  nor  is  it  of  consequence  that  we 
should  settle  the  question  in  advance.  There  is  no  one 
kind  that  is  better  than  all  others,  or  can  be  substituted  for 
all  the  rest.  One  kind  uses  one  set  of  muscles,  another  uses 
another  set.  Walking  employs  the  muscles  of  locomotion ; 
cutting  and  sawing  wood  exercise  the  muscles  of  the  arms 
and  shoulders.  Riding  on  horseback  employs  the  muscles 
of  the  lower  limbs,  back,  and  arms,  and  agitates  the  whole 
frame.  * 

673.  Walking   is  the  most  readily  accomplished,  and  is 
within  the  reach  of  every  one.     There  is  every  where  a  road 
or  a  field  to  walk  in ;  and  if  this  exercise  be  taken  with  due 
energy,  as  boys  and  young  men  usually  take  it,  moving  with 
alacrity,  swinging  the  arms  and  calling  into  requisition  the 
contractile  power  of  most  of  the  muscles  of  the  body,  it 
will  ordinarily  be  sufficient  for  the  maintenance  of  health. 
Walking  is  the  most  advantageous  when  it  is  bold  and  easy. 
The  body  should  be  carried   erect,  the   chest  allowed  the 
greatest  freedom  of  expansion.     The  arms  should  hang  and 
swing  freely  from  the  shoulders.     A  stooping  posture  inter- 
feres with  the  action  of  the  lungs ;  and  a  confinement  of  the 
hands,  the  folding  the  arms  on  the  chest,  or  carrying  them 
in  a  muff,  limits  the  muscular  exertion,   makes  the   move- 
ments unnatural,  and  causes  an  ungraceful  gait. 

674.  The  sports  of  boyhood,  the  games  of  the  street  and 
the    playground,    which    not   only    require   much    muscular 
exertion  but,  are  attended  with  exhilaration,  answer  all  the 


BONES,    MUSCLES,    EXERCISE    AND    REST.  293 

purposes  of  health.  By  custom  and  the  general  opinion  of 
society,  boys  are  thus  happily  indulged.  They  are  allowed 
and  encouraged  to  run,  jump,  and  leap,  and  even  to  shout. 
They  are  consequently  in  good  health,  and  have  great  vigor 
of  body  and  activity  of  motion. 

-675.  But  the  custom  of  society  and  the  notions  of  pro- 
priety demand  a  different  manner  from  the  girls.  They  are 
not  permitted  to  walk  with  that  energy  and  vigor  that  their 
brothers  are.  There  is  a  great  fear  of  romping.  They  are 
required  to  be  staid  and  quiet,  and  to  confine  themselves 
to  walking.  They  are  prohibited  from  the  noisy  plays,  the 
bold  activity  of  motion,  and  that  free  exercise  of  the  lungs, 
which  strengthen  and  delight  the  boys.  And  while  the  boys 
.an  and  pursue  any  object  of  interest  through  the  roads  and 
fields,  over  rocks  and  hills,  the  girls  are  required  to  limit 
their  movements  to  walking  on  the  smooth  and  level  paths 
which  require  comparatively  little  exertion. 

676.  A  walk  of  three  miles  is  not  frequent  for  American 
women ;  and,  when  a  lady  of  a  country  town  of  New  England 
walked  sixteen  tniles  at  once,  in  the  year  1842,  it  was  con- 
sidered so  extraordinary  as  to  be  made  the  subject  of  a  news- 
paper article.     But  in  England,  a  walk  of  some  miles  is.  an 
every-day  occurrence  for  women ;  and  thus  they  have  means 
of  locomotion  ever  at  their  command.     When  an  American 
clergyman  was  visiting  a  family  in  England,  it  was  proposed 
by  the  young  ladies  to  visit  a  friend  who  lived  at  the  distance 
of  five  or  six  miles.     He  cheerfully  consented,  but  was  sur- 
prised that  no  carriage  came  to  the.  door.      They  walked, 
and  spent  a  part  of,  a  day  with  their  friend.     On  returning, 
the  ladies  proposed  to  the  clergyman  that  they  take  another 
way  homeward,  which  would  make  a  walk  of  three  miles 
farther,  and  call  on  another  friend.     He  consented,  and  they 
went  this   long,  and,  to  him,  wearisome  w,ay  home.      The 
females  neither  -regarded  the  walk,  nor  even  seemed  to  think 
they  had  done  any  thing  extraordinary,  or  out  of  their  usual 
habit;  but  the  American  gentleman  was  unusually  fatigued. 

677.  Same  other  employments  give  more  exercise  to  the 
arms  and  upper  part  of  the  frame  than  walking.     Garden* 

25* 


294  PHYSIOLOGY    AND    HEALTH. 

ing,  raking,  hoeing,  and  digging,  call  into  play  the  muscles 
of  the  arms,  shoulders,  and  back.  Working  with  the  car- 
penter's and  cabinet-maker's  tools  has  the  same  effect,  and 
when  either  of  these  can  be  combined  with  walking,  the 
best  effects  upon  the  health  are  obtained. 

678.  Dancing,  when   practised    at  proper  hours,  and  in 
sufficiently  ventilated   rooms,  is   an   excellent  exercise.     It 
brings  many  muscles  into  action,  and  it  is  usually  attended 
with  cheerful  exhilaration, -that  quickens  the  flow  of  blood 
and  increases  respiration.     But  the  mere  practising  of  atti- 
tudes, or  the  walking  quietly  through  the  figures,  gives  no 
exercise;  and   the   late   hours,  crowded   rooms,   and   night 
suppers,  too  often    connected  with  this  amusement,  render 
it  of  very  doubtful  utility,  if  not  certainly  injurious. 

679.  To  the  hardy  and  laborious,  it  may  seem  a  matter 
of  indifference  whether  we  take  exercise  at  one  or  another 
hour   of  the  day;  and,  for  those  who  work   from  morning 
till  night,  all  hours  are  alike  in  this  respect.     Still,  for  the 
invalid,  and  for  those  who  only  exercise  for  a  short  period, 
and  for  the  maintenance  of  health,  all  hours  are  not  equally 
advantageous.     It  is  common  to  recommend  the  morning  as 
the  time  to  walk.     The  freshness  of  the  morning  air  has  been 
the  song  of  the  poet,  the  therne  of  the  moralist,  the  faith  of 
the  philosopher.     All  have  conspired  in  its  praise,   and  in 
urging  upon  the  feeble   and   the  sedentary  the  beauty  and 
advantage  of  early  action  abroad. 

680.  The  morning  may  be  the  time  for  exercise  of  some, 
but  it  is  not  the  best  time  for  all.     After  the  long  fasting  of 
the  night,  .the  body  requires  nourishment  before  it  labors. 
(§  113,  p.  56.)     It  is  apt  'to  faint  if  it  works  before  break- 
fast.    Beside,  the  dews  and  dampness  of  the  night,  and  the 
exhalations  which  have  arisen  from  the  earth,  are  upon  the 
morning  air,  and  must  enter  the  lungs  of  those  who  are  then 
abroad,  and  prevent  their    receiving  the  refreshing  invigo- 
ration  which  a  walk  at  another  hour  would  give  them.     The 
same  objection    applies  to  evening  and  the  night,  and  the 
sedentary    should   not   then   take   their    excursions    in    the 
open  air. 


.       BONES,    MUSCLES,    EXERCISE,    AND    REST.  295 

681.  The  state  of  the  digestive  organs  should  be  regarded 
when  we  exercise.  We  should  not  work  just  before  eating, 
especially  if  we  have  long  fasted  and  are  hungry,  for  then 
the  system  is  comparatively  weak,  and  needs  nourishment, 
and  is  therefore  easily  exhausted  by  exertion.  And  more- 
over, muscular  action  would  expend  the  nervous  energies 
that  should  be  reserved  to  sustain  the  stomach  in  digesting 
the  coming  meal.  (§  104,  p.  77.)  Neither  should  we  exercise 
immediately  after  eating,  for  the.  work  of  digestion  requires 
all  the  energies  of  the  system,  until  the  food  becomes  thor- 
oughly mixed  with  the  gastric  juice. 


CHAPTER   XIII. 

Place  for  Exercise.  —  Should  not  be  in  House,  but  in  open  Air. — 
Exercise  should  be  frequent  and  regular.  —  All  need  it,  especially 
the  Sedentary.  —  Consequences  of  Neglect. 

682.  WE  need  an  abundant  supply  of  oxygen  to  sustain 
the  increased  demand  for  nutrition  and  discharge  of  waste 
which  is  caused  by  muscular  action.     Exercise  abroad  in  the 
open  air  gives  more  health  and  vigoi  to  both  body  and  mind 
than  exercise  in  the  house.     Some  have  prepared  gymnastic 
apparatus  in  their  garrets,  or  in  their  cellars,  in  order  that 
they  and  their  families  may  exercise  without  the  trouble  and 
exposure  of  going  out  of  doors.     Some  gentlemen  in  cities 
saw  and  split  wood  in  their  cellars ;  but  they  fail  of  obtaining 
the  full    measure  of  good   that   action   in  open   air   would 
give  them.     Even  those  mechanics  whose  employments  give 
them  sufficiency  of  muscular  exercise,  especially  those  who 
work  in  close  shops,  would  do  well  to  add  a  walk  abroad  to 
their  in-door  labors;  for  they  would  gain  in  vigor  of  body,  and 
freshness  of  spirit,  and  effective  power,  more  than  sufficient 
to  compensate  for  the  loss  of  time  devoted  to  their  renovation. 

683.  Whatever  may  be  the  weather  or  the  season,  the 
demand  of  the  system  for  exercise  abroad  is  the  same;  for 


296  PHYSIOLOGY    AND    HEALTH. 

we  have  the  same  wants,  and  need  the  invigorating  effects  of 
muscular  action  both  winter  and  summer  —  in  fair  weather 
and  in  foul.  Nor  is  there  any  sufficing  objection  to  it,  for 
very  few  days  of  the  winter  are  so  cold  that  we  cannot  keep 
ourselves  comfortable  by  rapid  walking,  or  other  exertion , 
and,  indeed,  the  colder  the  weather  the  more  dense  is  the 
air,  and  the  greater  quantity  of  oxygen  is  received  into  the 
lungs  to  sustain  the  internal  fire.  (§  444,  p.  189.)  Very  few 
days  are  so  stormy  as  to  prevent  this  exercise  abroad,  and  on 
such  days  it  may  be  taken  under  cover  of  the  house. 

684.  This  law  for  the  health  of  the  frame,  and  the  neces- 
sity of  exercise  abroad,  is  one  and  the  same  for  both  male 
and  female,  for  the  rich  and  the  poor.     All  can  have  a  fuller 
development  of  strength,  and  health,  and  life,  by  taking  it 
abroad ;   and  all  must  suffer  the  same  depreciation  of  life  if 
they  neglect  it.     There  are  none  so  favored  in  life  as  not  to 
need  it,    none  so   high    as  not  to  be  benefited  by    it,  and 
very  few  so  feeble  as  not  to  be  able,  in  some  degree  or  other, 
to  obtain  it. 

685.  Exercise  should  be  frequent  and  regular.     The  sys- 
tem wants  this  means  of  invigoration  as  regularly  as  it  wants 
new  supplies  of  food   for  nutrition.     Every  day,  therefore, 
should  have  its  own,  and  no  day  should  have  more.     It  is  not 
enough  for  health  that  we  live  inactively  for  several  days,  then 
devote  one  day  to  action  of  the  muscles.     But  many  do  so; 
they  have,  in  all,  a  sufficiency  of  exercise,  but  they  take  it 
irregularly.     A  clergyman,  of  .very  studious  habits,  devoted 
Mondays  to  walking,  or  riding  on  horseback,  and  the  rest  of 
the  week  to  mental  labor.    While  writing  his  sermons,  he  often 
for  three  days  scarcely  left  his  room.     He  became  dyspeptic. 
Some  teachers  labor  incessantly  in  their  vocation  for  weeks 
successively.     They  teach  six  hours  daily  in  school,  and  read 
and  study  the  other  waking  hours  out  of  it,  with  the  intention 
of  devoting  their  vacation  to  excursions  and  labor,   arid  then, 
they  think,  they  shall  get  exercise  enough  for  another  term 
of  confinement. 

686     The  industrious  seamstress,  earning  her  scanty  pit 


BONES,     MUSCLES,    EXERCISE    AND    REST.  297 

tance  by  incessant  toil :  the  shoemaker,  working  the  whole 
day  upon  his  bench;  the  mother,  watching  over  her  sick  child; 
the  faithful  minister,  writing  for  his  people ;  and  the  judge, 
trying  the  issues  of  life  and  death  —  suffer  as  surely  from  in- 
door confinement,  and  want  of  daily  exercise  abroad,  as  the 
indolent,  who  have  no  occupation  and  no  call  for  action. 
These  must  fall  short  of  that  full  measure  of  power  of  body 
and  of  mind  to  do  their  present  and  pressing  work,  which  a 
proper  attention  to  the  wants  of  the  body  would  have  given 
them.  They  may  think  they  have  no  time  for  recreation 
abroad,  and  that  an  hour  a  day,  spent  in  mere  walking,  is  so 
much  waste  of  opportunity  of  usefulness  or  of  profit.  But 
it  is  not  so;  the  time  required  for  the  repair  of  the  vital  ma- 
chine is  not  lost,  for  the  body  will  not  work  the  most  easily, 
and  with  its  fullest  energy  and  most  successful  effect,  if  it  is 
not  in  the  best  order.  None  need  this  daily  recreation  more 
than  those  who  are  compelled  to  produce  every  day  the 
greatest  result  from  mental  or  physical  in-door  labor,  and  who 
want,  for  that  purpose,  the  fullest  vigor,  both  of  their  muscular 
and  nervous  systems,  and  the  most  complete  control  of  their 
powers. 

687.  The   evil   consequences    of   neglect    of   exercise    are 
not  sudden   nor  immediately  perceptible.     They  are  gradual 
and  accumulative.    They  steal  slowly  upon,  and  secretly  bind 
the  strong  man,  and  then  take  away  his  health.     Dyspepsia, 
defective  nutrition,  muscular  weakness,  nervous  irritability, 
and  mental  dulness,  so  manifest  and  oppressive  as  to  compel 
the  sufferer  to  change  his  pursuits  or  his  habits,  and  betake 
himself  to  some  means  of  relief,  are  remote  results.     But  the 
immediate  effects,  however  small  and  unnoticed,  are  none  the 
less  sure  to  come,  and  diminish  the  activity  and  force  of  life 
in  proportion  to  the  neglect.     If  this  is  continued,  and  vio- 
lation of  thi?  law  is  frequent,  weakness  necessarily  follows, 
until  marked  and  acknowledged  disorder  is  established. 

688.  It  must  be  now  considered  as  established  that  a  cer- 
tain quantity  of  muscular  exercise  is  necessary  for  the  main- 
tenance of  health,  and  for  the  best  performance  of  the  funo 


293  PHYSIOLOGY    AND    HEALTH. 

tions  of  digestion,  respiration,  nutrition,  and  of  the  brain. 
The  amount  of  this  exercise  may  vary  according  to  the  con- 
stitution, and  habit,  and  powers  of  the  individual.  It  is  best 
when  so  varied  as  to  bring  into  play  all  the  muscles  of  the 
body.  It  should  be  taken  out  of  doors,  and  in  the  free  air. 
This  is  necessary  for  all  men  and  all  women,  of  whatever 
occupation,  and  especially  for  those  of  no  occupation. 


CHAPTER  XIV. 

Amount  of  Exercise  may  be  greater  than  Health  requires.  —  Body 
grows  strong  with  judicious  Labor.  —  Limit  to  Man's  Increase  of 
Strength.  —  Fulness  of  Strength  maybe  maintained  to  Old  Age, 
with  proper  Care.  —  Man  has  a  limited  Power  of  Endurance. — 
No  more  Strength  must  be  expended  in  the  Day  than  is  restored 
in  the  Night.  —  Men  worn  out  by  excessive  Toil.  —  Length  of 
Life  differs  with  Amount  of  Labor. 

689.  THAT   amount 'of  exercise  which   is  necessary  for 
health  is  not  the  limit  of  muscular  power.     If  it  were,  we 
should  be  able  to  accomplish  but  a  small  part  of  the  work 
which  we  now  do,  and  the  labors  of  the  farm  and  workshop 
would  not  be  effected.     We  have  a  power  of  muscular  con- 
traction and  of  motion,  which  may  be  applied  to  the  ordinary 
purposes  of  life.     With  this  we  cultivate  the  soil  and  carry 
on  the  operations  of  the  mechanic  arts,  we  navigate  ships, 
and  perform  all  our  labor  for  pleasure  or  for  profit. 

690.  It  becomes  a  question  to  every  man  who  works  for 
profit,  or  who  exercises  more  than   is  needed   for  the   bare 
maintenance   of  health,   how    much    can    he  work  ?     Have 
the  moving  animal  frame,  the  muscles  and  the  bones,  an  in- 
definite power. of  endurance  and  action?     It  needs  no  physi- 
ological  explanation  to  show  that  there   is  a  limit  to  this 
power  of  labor.    Then  there  comes  another  question  —  Where 
is  that  limit?     How  long  can  a  man  labor  ?     How  much  may 
he  labor  each  day,  and  not. wear  upon  his  permanent  health, 
nor  interfere  with  his  continuance  of  life?     To  a  certain 


BONES,    MUSCLES,    EXERCISE    AND    REST.  299 

extent,  the  body  grows  strong  with  labor,  and  every  exertion 
adds  new  particles  and  power  to  the  muscular  fibre.  The 
man  who  walked  to  Niagara  Falls  (§  668,  p.  281)  was  stronger 
the  second  day  than  he  was  the  first,  and  stronger  the  third 
than  the  second.  He  began  with  a  power  to  walk  three 
miles,  and  ended  in  six  weeks  with  a  power  to  walk  forty 
miles.  Whether  he  could  have  added  still  more  to  this 
power,  or  how  much  stronger  he  could  have  grown,  is  not 
known,  for  the  experiment  was  not  tried  any  further.  In  the 
same  manner,  any  one  unaccustomed  to  labor,  if  he  has  a 
good  constitution  and  health,  and  if  he  proceeds  gradually, 
and  cautiously  increases  from  small  beginnings,  can,  in  time, 
become  sufficiently  strong  to  do  the  ordinary  agricultural 
labor. 

691.  In  this  process  of  invigoration  there  may  be  fatigue, 
but  there  must  be  no  languor  nor  exhaustion.     But  if  either 
of  these  happens,  —  if  the  working  man  finds  himself  exhausted 
after  his  toil,  if  he  is  uneasy,  and  restless,  and  unable  to  sleep, 
and  awakes  the  next  morning  unrefreshed  and  unprepared 
for  new  exertion,  —  he  may  be  sure  that  he  has  overworked  his 
frame,  and  reduced  rather  than  increased  his  strength. 

But  by  faithful  and  prudent  use  of  the  power  already 
gained,  by  never  over-working  on  any  one  day,  by  always 
stopping  short  of  exhaustion,  additions  are  made  to  the 
strength  day  by  day,  for  a  certain  period  and  to  a  definite 
extent.  The  laborer  may  increase  his  exertion  as  long  as 
he  feels  this  increase  of  power.  But  there  must  be,  and  is, 
a  limit  to  this.  No  man  grows  infinitely  strong,  and  sooner 
or  later  he  must  reach  the  end  of  his  growth  of  power;  then 
he  possesses  his  fullest  measure  of  strength. 

692.  Having  arrived   at  this  fulness  of  strength,  he  can 
maintain  it  if  he  uses  it  discreetly  and  temperately,  and  if  he 
exercises  daily,  but  never  expends  in  any  one  day  more  than 
its  due  portion  of  power.     By  this  self-management,  a  man 
can  keep  himself  in  the  highest  working  order,  and  he  will 
be  able  to  accomplish  the  most  labor,  not  in  any  one  day,  nor 
in  a  single  year  merely,  but  in  the  whole  course  of  life,  and 


300  PHYSIOLOGY    AND    HEALTH. 

protract  that  life  and  its  full  working  power  to  the  natural 
period.  For  this  end,  he  must  attend  to  the  first  sensation 
of. weariness,  and  never  permit  it  to  increase  to  exhaustion; 
and,  whenever  he  begins  to  feel  this,  he  may  understand  that 
the  waste  of  life  has  reached  the  measure  of  the  nutrition ; 
and,  if  he  then  stops  and  rests,  this  last  will  go  on,  and  he  will 
in  due  time  be  refreshed  and  ready  again  for  labor.  In  this 
way,  he  will  always  work  at  the  full  flow  of  his  strength,  and 
be  able  to  perform  the  greatest  amount  of  labor. 

693.  There  is  a  common  and  mistaken  notion,  that  man 
has  an  indefinite  power  of  endurance,  and  may  work  until 
fatigue  or  exhaustion  compels  him  to  stop  ;  and  that  whatever 
strength  is  riot  used  in  the  hour  and  in  the  day,  and  is  car- 
ried to  the  bed  at  night,  is  so  much  lost.     Therefore  some 
weak  men  labor  as  long  as  their  strength  holds  out,  and  some 
strong  men  labor  as  long  as  the  day  will  permit  them.     In 
consequence  of  this  daily  fatigue  and  exhaustion,  they  are 
never  in  full  vigor,  they  are  always  reduced  somewha',  below 
their  natural  standard,  and  commence  each  day  with  a  lower 
energy,   and  work  upon   a  lower  tide  of  power,  than  they 
otherwise  might  have  done. 

694.  By  this  excess  of  labor,  a  man  expends  more  strength 
in  the  day  than  he  recovers  in  the  night,  and  rises  unrefreshed 
in  the  morning.    He  is  wasting  his  constitution,  and,  if  he  per- 
severes, he  reduces  himself  to  a  lower  standard,  and  then  he 
is  compelled  to  limit  his  exertions  and  perform  lighter  labors. 
In  this  reduced  and  weakened  condition,  he  may,  by  proper 
management  of  his  diminished  strength,  lead  a  life  of  con- 
siderable action,  and  perhaps  regain  his  original  vigor.     Or 
he   may,   by  still    overworking,   reduce   himself  below   the 
power  of  labor,  and,  becoming  decrepit,  suffer  the  pains  and 
debilities  of  old  age  long  before  his  time. 

695.  Those  overworked  and  exhausted  men,   completely 
broken  down  and  unable  to  labor,  are  not  very  common,  yet 
they  may  be  found.     A  farmer,  within  my  observation,  began 
his  life  with  small  means,  but  with  great  energy  and  large 
hope.     He  seemed  to  think  there  could   be  no  end  to  his 


BONES,    MUSCLES,    EXERCISE    AND    REST.  301 

power  and  labor.  He  rose  with  the  sun  in  summer,  and  let 
it  go  down  upon  his  toil.  He  allowed  himself  a  few  hours 
for  sleep,  and  a  few  minutes  for  food,  and  no  time  for  di- 
gestion. But  in  a  few  years  he  was  worn  out,  and  was  then 
and  afterwards,  in  health  and  strength,  an  old  man.  For  the 
rest  of  his  years  he  was  an  invalid,  and  unable  to  undertake 
even  the  lightest  labor  of  his  farm.  Such  instances  of  com- 
plete waste  of  power  by  excess  of  labor  may  be  rare,  yet  the 
lesser  degree  of  exhaustion  is  very  prevalent.  We  find  many 
who,  after  the  middle  period  of  life,  feel  obliged  to  favor 
themselves,  and  do  lighter  work,  and  with  more  frequent  in- 
tervals of  rest  than  others,  because  they  have  overworked  and 
expended  their  power;  and  there  are  not  many  laborious 
men  who  do  not  thus  begin  to  slacken  in  their  labors  soon 
after,  perhaps  before,  they  have  passed  their  fiftieth  year. 

696.  This  constant  labor,  not  only  wastes  the  strength,  but 
breaks  up  the  constitution,  and  finally  disarms  it  of  its  power 
of  resistance  to  the  causes  of  death.     Hence  the  life  of  the 
overwrought  laborer  is,  in  general,  shorter  than  that  of  the 
moderate  worker.     According  to  the  registration  of  deaths  in 
Massachusetts,  for  the  20  years  and  8  months  ending  with 
1863,  it  seems  that  the  average  length  of  life  is  the  shortest 
with  those  classes  of  men  whose  days  are  spent  in  the  severest 
toils.    The  ages  and  professions  of  men  are  recorded  in' these 
registers ;  and  from  these  we  learn  that  19,252  farmers  died  at 
the  average  age  of  64  years  and  37  days;  14,733  common  day 
laborers,  at  the  average  age  of  45  years  and  11£  months  ;  and 
5070  sailors,  at  the  average  age  of  45  years  and  8  months. 

697.  The  farmer  is   not  obliged  to  make  so  continued 
and  unremittingly  severe  exertions  as  the  day  laborer.     He 
has  a  capital  in  store,  and,  in  jnost  cases,  can  have  help  at 
command,  and  suspend  his  own  labor,  or  take  the  lighter 
tasks.     But  for  the  laborer,  each  day's  bread  must  be  ob- 
tained by  that  day's  toil.     To  him  there  is  allowed  no  rest 
nor  choice  of  work;    and  to  him  is  usually  assigned  the 
heaviest  and  the  hardest.     The  sailor  is  presumed  to  be,  in 
all  cases,  a  man  of  full  strength.     He  must  assume  his  share 

'26 


302  PHYSIOLOGY   AND    HEALTH. 

of  the  ship's  labor,  and  perform  a  stout  man's  duty.  He 
must  take  his  turn,  and  watch  night  as  well  as  day.  He  can 
never  expect  to  have  an  entire  night's  rest. 

Making  all  due  allowance  for  the  difference  of  habits  of 
many  in  these  several  classes,  —  admitting  that  the  poor  la- 
borer is  often  an  invalid,  and  is  worse  clothed  and  fed  than 
the  farmer,  and  that  more  accidents  happen  to  both  the  laborer 
and  the  sailor  than  to  the  farmer,  and  even  other  circum- 
stances that  interfere  with  the  full  enjoyment  of  health,  —  still 
much  of  this  great  difference  of  longevity  —  a  measure  of 
years  on  earth  given  to  the  farmer  about  forty  per  cent, 
greater  than  that  given  to  the  laborer  and  the  sailor  —  must 
be  charged  to  that  excess  of  toil  which  wears  out  the  man 
prematurely. 


CHAPTER      XV. 

Languor  always  succeeds  great  Efforts.  —  Serious  Injury  may  follow. 
—  Growing  Children  need  various  and  light  Exercises.  —  Youths 
cannot  endure  the  full  Labor  of  mature  Men. 

698.  THE  period  of  vigor  and  of  a  man's  productive 
power  is  shortened,  the  sum  of  the  whole  life's  exertion  is 
materially  diminished,  and  its  last  stages  rendered  compara- 
tively useless,  by  attempting  to  work  beyond  the  power  of 
permanent  endurance.  This  is  the  result  of  long-continued 
over-exertion.  But  even  if  it  is  not  long  continued,  if  it  is 
merely  temporary,  the  same  result  of  languor,  and  lessened 
ability  for  labor,  follows  for  a  proportion  ably  short  period. 
An  extraordinary  labor  of  one  day  is  followed  by  extraor- 
dinary languor  the  next;  and  whether  this  greater  exertion, 
this  excess  of  waste  of  the  powers  over  the  nutrition,  be  more 
or  less,  it  must  be  followed  by  a  proportionate  feebleness. 

099.    Excessive  temporary  exertions  are  followed,  not  only 


BONES,    MUSCLES,    EXERCISE,    AND    BEST.  303 

by  a  corresponding  languor,  but  sometimes  by  serious  injury 
to  the  constitution.  We  are  sometimes  told  by  men  that, 
since  they  strained  themselves  by  lifting,  or  running,  or  by 
violent  working  at  a  fire,  or  some  other  occasion,  they  have 
not  enjoyed  their  former  health,  nor  have  been  able  to  work 
with  their  former  energy.  These  evil  consequences  more 
frequently  follow  the  excessive  efforts  of  boys  and  young 
men.  Dr.  Hope  says,  that  violent  corporeal  efforts,  of  every 
description,  accelerate  the  circulation,  and  cause  an  unnatural 
pressure  of  blood  upon  the  heart.  "  In  growing  youths,  ex- 
cessive rowing  is  one  of  the  most  efficient  causes  of  this 
disturbance  of  the  heart.  Violent  gymnastics  produce  the 
same  effect."* 

700.  The  natural  exercises  of  children,  their  sports  and 
games,  which  they  enter  upon  and  go  through  with  boisterous 
zeal,   give  them  light,  and  varied,  and  sufficient  muscular 
action.     None  of  the  muscles  are  tasked  too  much,  none 
called  to  labor  for  any  length  of  time.     Children  and  youth 
are  not  made  for  hard  labor ;  whatever  work  is  required  of 
them    should   be  light,  varied,  and   short.     Great  exertion 
during  the  forming  and  growing  period  would  very  soon  ex- 
haust their  strength,  and,  if  continued,  it  would  prevent  the 
full  development  and  growth  of  the  muscular  system,  and 
even  wear  down  the  constitution. 

701.  A  man  does  not  reach  his  full  measure  of  strength 
and  power  of  endurance  until  he  has  passed  his  25th  year. 
And  if,  under  that  age,  he  is  exposed  to  the  hard -labor  and 
privations  which  older  men  seem  to  endure  with  impunity, 
and  in  situations  where  can  be  no  relaxation  nor  favor  shown, 
the  health  and  strength  of  the  youth  fail ;  and,  if  there  is 
danger  from  the  labor  and  exposure,  the  youth  is  the  first  to 
die.     Young  soldiers  sink  under  the  labors  and  privations  of 
the  camp  sooner  than  mature  men.     Napoleon  complained 
that  boys  were  sent  to  supply  his  army,  rather  than  men  who 
could  endure  the  toils  and  the  sufferings  of  the  campaign. 

*  Diseases  of  the  Heart,  Part  III.  Chap.  1. 


304  PHYSIOLOGY    AND    HEALTH. 

TJie  development  of  strength  is  progressive  through  the 
several  periods  of  early  life,  and  each  period  has  its  appro- 
priate means  and  opportunities.  The  plays  of  childhood 
prepare  the  muscles  for  the  light  employments  of  youth  ; 
these  increase  the  muscular  energies,  and  prepare  them  for 
the  full  power  of  labor  in  manhood.  Each  is  necessary,  and 
none  can  be  omitted,  nor  can  they  be  interchanged.  Some 
children  are  exclusively  devoted  to  study,  and  have  no  incli- 
nation to  active  play.  They  prefer  their  books,  while  other 
children  are  playing  abroad.  These  develop  their  nervous 
systems,  but  their  muscular  powers  are  dormant.  They 
become  good  scholars,  but  are  weak  in  body,  and  ultimately 
their  mental  energies  sometimes  falter. 


CHAPTER  XVI. 

Labor  requires  healthy  Organs  of  Digestion  and  Nutrition.  —  Good 
Food,  sound  Lungs,  and  fresh  Air.  —  Healthy  Skin,  sound  Con- 
dition, and  Cooperation  of  the  Brain  and  Nervous  System.  —  Exer- 
cise most  beneficial  when  the  Brain  is  lively  and  Spirits  cheerful. 

702.  MUSCULAR  action  presupposes  waste,  (§  252,  p.  115,) 
which  is  supplied  immediately  from  the  blood,  and  remotely 
from  the  food.     The  active  have,  comparatively,  new  flesh, 
and  the  inactive  old  flesh.  (§  257,  p.  117.)     In  order  to  sup- 
ply this  waste,  and  make   new  muscular   atoms,  the  organs 
that  effect  the  changes  in  the  food,  and  the  channels  through 
which  it  passes  in  its  progress  from  its  condition  as  food  in 
the  mouth  to  its  new  condition  as  flesh  in  the  tissues,  should 
be  in  good  health.    A  working  person  must,  therefore,  have  a 
sound  stomach  and  good  digestion.    The  organs  of  circulation 
and  nutrition  must  also  be  in  good  order ;  for  otherwise  the 
food  cannot  be  converted  into  blood,  nor  the  blood  into  flesh, 
to  meet  the  changes  that  the  action  of  the  muscles  demands. 

703.  Next   in   importance  to   a  sound   condition   of  the 
organs  of  digestion  and  nutrition  is  the  supply  of  good  food. 
Food  alone  is  the  source  of  all  our  bodily  strength ;  and  it 


BONES,    MUSCLES,    EXEECISE,    AND    REST.  305 

gives  this  power  only  in  proportion  as  it  can  be  converted 
into  new  atoms  of  flesh.  The  laboring  man  wants  rich  and 
nutritious  food  to  sustain  him  in  his  exertions.  He  cannot 
work  with  his  fullest  energy  with  poor  and  innutritions  ali- 
ment. Just  in  proportion  as  his  diet  is  low  or  lacks  in  nutri- 
ment, must  his  strength  and  his  power  of  labor  fail.  The? 
English  trainers,  who  develop  the  greatest  muscular  force, 
eat,  or  give  their  men  the  best  of  bread  and  the  best  of  meats, 
—  beefsteak  and  mutton.  On  the  same  principle,  the  judi- 
cious but  economical  farmer  feeds  his  cattle,  and  gives  the 
oxen  that  work  better  hay  than  those  that  lie  still. 

704.  The  laborer  not  only  wants  nutritious  food,  but  that 
which  can   be   converted   into  flesh   with    the    least   cost    of 
power.     Digestible   food  requires   but  little  exertion  of  the 
stomach  to  convert  it  into  chyle;    but  heavy  bread,  tough 
meats,  matters  that  are  badly  cooked,  and  all  other  sorts  of 
food  that  are  hard  to  be  digested,  are  not  converted  into 
chyle  without  much  labor.     If  more  strength,  or  more  nervous 
power,  is  expended  in  digestion,  of  course  less  can  be  ex- 
pended upon  the  muscles  of  motion.     This  is  well  understood 
when  one  has  eaten  a  very  heavy  dinner,  which  absorbs  all 
the  energies  of  the  system  for  its  digestion.     Then  he  can  no 
more  work  with  his  hands  than  he  can  when  he  is  using  his 
feet  with  all  his  force.     The  same  is  true,  though  in  a  lesser 
degree,  when  any  food  that  is  of  difficult  digestion  is  taken. 
While  this  is  going  on,  the  man  may  work,  but  his  power  of 
labor  is  reduced  in  proportion  to  the  difficulty  of  the  digestive 
operation.     A  person,  therefore,  can  accomplish  the   most 
when  he  has  eaten  light  bread  and  the  best  pieces  of  meat ; 
and  the  laboring  man,  whose  life  is  in  his  power  of  labor, 
can  afford  to  eat  no  other. 

705.  The  waste  caused  by  exercise  must  find  free  outlet 
through  the  skin  and  the  lungs.     Both  these  organs  must, 
then,  be  in  a  healthy  condition  in  the  laborer.     His  surface 
must,  by  frequent  bathing,  be  kept  free  from  every  thing  which 
would   clog  its  pores,  or  obstruct  its  operations.     The  in- 
creased waste  through  the  lungs  demands  a  greater  supply 

26* 


306  PHYSIOLOGY    AND    HEALTH. 

of  oxygen,  and,  consequently,  a  more  frequent  respiration 
during  exercise.  But  if  the  lungs  are  unsound,  or  inflamed, 
or  in  any  way  impaired,  or  if  their  motions  are  impeded  by 
any  external  incasement  around  the  chest,  they  cannot  re- 
ceive air  sufficient  to  carry  off  the  excess  of  wasted  particles 
which  are  thrown  into  them.  For  this  cause,  a  man  laboring 
under  asthma  or  consumption  cannot  run,  or  pump  at  a  fire- 
engine,  or  mow  grass,  or  perform  any  labor  that  requires 
great  and  continuous  effort.  An  abundant  supply  of  pure  air 
is  equally  necessary  to  carry  off  the  excess  of  waste.  Men 
who  work  in  close  shops,  mines,  and  the  holds  of  ships,  have 
less  power  than  those  who  work  in  the  fields. 

706.  The  heart,  being  the  engine  that  propels  the  blood, 
is  required  to  work  with  greater  force  and  rapidity  when 
exercise  demands  a  greater  supply  of  nutriment  in  the  tis- 
sues.     If  this  organ  is  unsound,  it  cannot  make  this  extra- 
ordinary exertion  ;  and  those  who  have  diseased  hearts  cannot 
perform  very  active  labor.     Mr.  H.,  a  very  industrious  farmer, 
once  complained  to  me  "  that  he  could  not  cut  his  wood, 
nor  mow  his  grass,  as  he  had  done,  for  the  exertion  imme- 
diately caused  great  distress  about  the  region  of  the  heart, 
and  then  he  could  not  move."     He  was  suffering  from  a  dis- 
ease of  the  heart,  of  which  he  afterwards  died. 

707.  The  brain  is  connected  with  all  the  muscles  through 
the  medium  of  nerves,  and  directs  and  sustains  their  motions. 
The  state  and  health  of  the  brain  and  mind  affect,  very  ma- 
terially, the  value  of  exercise  and  the  power  of  labor.     We 
will,  or  determine,  to  move  the  finger ;    at  the  same  instant 
the  volition  is  sent  from  the  brain  to  the  muscle  that  moves 
the  finger ;  this  then  contracts,  and  the  finger  moves.     This 
is  the  case  with  all  voluntary  motion  ;  yet  the  volition  of  the 
mind   and  the  action  of  the  brain  are  not  always  observed. 
Some  motions  are  performed  so  much  from  habit,  that  we  are 
unconscious  of  the  volition.     When  we  walk,  we  contract  the 
muscles,  those  which  bend  the  joint  of  the  hip,  the  knee,  and 
ankle,  of  one  side ;  and,  at  the  same  moment,  we  contract  the 
muscles  which  straighten  these  joints  on  the  other  side.     At 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  307 

the  next  moment  we  reverse  this  action,  and  contract  the 
straightening  muscles  of  the  first  side  and  the  bending  mus- 
cles of  the  opposite  side ;  by  these  motions  on  opposite  sides, 
the  limbs  are  lifted  and  carried  one  before  the  other,  alter- 
nately, and  the  body  moves  onward. 

708.  While  we  walk  easily  over  a  smooth  and  familiar 
path,  we  may  direct  the  energies  of  the  brain  partially,  but 
not  exclusively,  to  other  matters,  and  talk  or  think  of  agree- 
able and  interesting  subjects.     But  if  the  walk  becomes  diffi- 
cult, —  if  the  mind  is  required  to  pick  the  way  through  wet  or 
stony  places,  or  perform  any  severe  labor,  —  all  the  energy 
of  the  brain  is  required  to  direct  and  sustain  the  muscles  of 
motion,  and  then  conversation  and   thought   are   suspended. 
But  if,   on   the  contrary,  the  brain  is  all  absorbed  with  other 
subjects,  —  if  we  are  engaged  in  deep  thought  or  oppressive 
anxiety,  —  the  muscular  contraction  is  not  so  easily  effected 
and  controlled,  the  strength  of  the  muscles  is  not  so  well 
sustained,  the  exertion  wears  more  upon  the  body,  and  con- 
sequently exercise  under  such   circumstances  is  not  so  in- 
vigorating, and  labor  not  so  effectual  and  profitable. 

709.  Although  the  brain  and  mind  must  not  be  absorbed 
or  oppressed  with  care  or  thought  when  we  exercise  or  labor, 
yet  they  should  not  be  dormant.     They  should  be  lively  and 
engaged.      The    exercise    should    have    an.  object.      Walks 
through  pleasant  scenes  and  among  interesting  objects,  ex- 
cursions in  pursuit  of  flowers,  minerals,  or  other  natural  ob- 
jects, do  more  for  the  health  than  those  which  have  no  object. 


CHAPTER   XVII. 

Labor  should  have  an  adequate  Object.  —  Hope  and  Confidence  give, 
and  Doubt  and  Fear  diminish,  Strength.  —  Cheerfulness  and  Mel- 
ancholy have  similarly  opposite  Effects.  —  Effect  of  Passion,  Al- 
cohol, on  Strength. 

710.  Labor  for  profit,   as   well  as   exercise  for   health, 
should  have  an  adequate  object.     The  mind  must  be  satis- 


308  PHYSIOLOGY    AND    HEALTH. 

fied,  or  else  the  brain  will  not  cooperate  with  its  full  energy, 
and  give  the  muscles  full  power.  When  the  farmer  fears 
that  the  cultivation  of  his  fields  will  produce  no  crop,  when 
the  laborer  believes  the  wages  are  inadequate  to  his  services, 
and  the  mechanic  thinks  his  wares  will  return  him  no  profit, 
they  cannot  make  their  greatest  exertions,  or,  if  they  do,  it  is 
at  a  cost  of  the  permanent  power.  But  the  laborer  who  is 
well  paid  generally  feels  a  motive  that  stimulates  the  brain, 
and  strengthens  the  muscles,  and  enables  him  to  work  vigor- 
ously and  successfully. 

711.  Hope  and  confidence  give  almost  unmeasured  strength ; 
but   despair    weakens,   almost    paralyzes.      When    a    man 
falls   overboard    at   sea,  he  swims  for  his   life   as   long    as 
he  has  hope  of  rescue  or  can  move  his  limbs,  until,  fatigued 
with  his  labor,  and  in  despair  of  obtaining  relief,  he  seems 
unable  to  swim  any  farther,  and  suspends  all  exertion,  and 
gives  himself  up  to  death.     But  if,  at  this  moment,  a  boat 
comes  in  sight,  or  land  appears  to  him,  a  new  hope  is  ex- 
cited, new  strength  is  given,  and  he  swims  again  with  a 
power  which  was  impossible  a  few  minutes  before. 

712.  The  same  effect  of  confidence  that  strengthens  the 
muscular  system,  and  of  doubt  that  weakens  and  sometimes 
paralyzes  exertion,  may  be  seen  in  any  of  the  labors  of  com- 
mon life.     If  the  student  walks  grudgingly,  with  doubt  as  to 
the  efficacy  of  the  exercise,  and  fear  that  he  is  misappropri- 
ating his  time ;  if  the  over-cautious  girl  walks  with  fear  lest 
the  exercise  flush  her  cheek  too  much,  or  the  perspiration 
soil  her  garments,  or  the  exercise  derange  her  dress ;  if  she 
moves  with  timid  anxiety  lest  she  assume  ungraceful   atti- 
tudes, or  in  any  way  transcend  the  becoming  delicacy  of  a 
lady,  —  the  brain  will  not  cooperate  earnestly  .with  the  work, 
nor  send  full  stimulus  to  the  muscles ;  the  limbs  then  labor 
languidly,  and  the  exercise  fails  to  invigorate  the  system. 

713.  Cheerfulness    and    melancholy    have    the    same    op- 
posing    effects   on    muscular   power    as    hope    and   despair, 
Whatever  depresses  the  spirits,  depresses  the  energies  of  the 
brain,  and  consequently  the  energies  of  the  locomotive  ap 


BONES,    MUSCLES,    EXERCISE,    AND    BEST.  309 

paratus.  The  slow  and  measured  step  of  the  funeral  proces- 
sion, and  the  light  "elastic  step  in  the  merry  dance,  are  both 
equally  indicative  of  the  energies  of  the  muscles.  There  is 
as  certain  a  difference  between  the  power  of  muscular  con- 
traction in  the  dancer  and  in  the  mourner,  as  there  is  between 
the  buoyant  spirit  of  the  one  and  the  oppressed  spirit  of  the 
other.  In  one,  the  heart  is  joyous,  the  brain  is  active,  and 
the  motion  quick  and  easy ;  -while  in  the  other,  the  heart  is 
sad,  the  brain  is  heavy,  and  the  movements  are  slow  and 
wearisome. 

714.  All  alcoholic  liquors  stimulate  the  muscular  ener- 
gies temporarily.  A  man  under  the  influence  of  these  can 
make  greater  exertions,  and  for  a  short  time  accomplish  more 
work.  But  this  increased  power,  like  the  effect  of  passion, 
is  of  very  short  duration.  While  stimulated  by  excitement, 
a  man  may  strike  heavier  and  quicker  blows ;  but  then  the 
unnatural  labors  soon  weary  and  exhaust  him.  All  his  ex- 
cessive exertions  make  a  draft  upon  his  permanent  constitu- 
tional power,  and  leave  him  weaker  than  they  find  him ;  and 
he  who  habituates  himself  to  depend  upon  the  stimulus  of 
spirit  to  give  him  strength  for  labor,  like  all  others  that 
overwork,  wears  himself  out  early,  and  brings  on  the  infirmi- 
ties of  age  before  the  natural  time. 


CHAPTER  XVIII. 

Attitudes.  —  Spine  supported  by  Muscles  equally  on  both  Sides.  — 
Spine  very  strong.  —  Porters.  —  Pedlers  carry  Burdens  on  Head, 
and  Spine  erect.  —  Centre  of  Gravity  over  Line  of  Support.  —  Head 
so  carried.  —  This  Attitude  easiest  and  most  graceful. 

715.  The  attitudes  assumed  in  exercise  or  labor  are  of  great 
importance.  The  structure  of  the  spine,  and  the  arrangement 
of  the  muscles  which  support  it,  give  this  column  its  greatest 
strength  and  flexibility  when  it  is  held  erect.  The  spine 
curves  from  back  to  front,  and  from  front  to  back  ;  yet  these 
curves  are  so  balanced  that  the  upper  end  of  the  column,  the 


310 


PHYSIOLOGY    AND    HEALTH. 


resting-place  for  the  head  in  its  natural  position,  is  vertically 
over  the  base  at  the  pelvis. 

716.  The  spine,  as  well  as  the  other  bones,  is  held  in  its 
erect  position  by  a  double  series  of  muscles,  (Fig.  LVH.,) 

FIG.  LVII.    Internal  Muscles  of  the  Back. 


a,  b,  Spinous  processes  of  the 
back-bone. 

c,  Longissinus  dorsi,  longest 
muscle  of  the  back. 

dt  Muscle  extending  from  the 
pelvis  tolhe  ribs. 

e,  Muscles  extending  from  the 
vertebrae  of  the  loins  to  those  of 
the  back. 

/,  gt  Muscles  extending  from 
the  vertebrae  of  the  back  to  those 
of  the  neck. 

h,  Muscle  extending  from  the 
back  and  neck  to  the  head. 


which  are  placed  on  both  sides  of  the  back-bone,  where  they 
form  a  cushion  of  flesh,  and  are  easily  felt.  The  lowermost 
of  these  are  fixed  by  one  end  to  the  hips,  and  by  the  other  to 
some  of  the  bones  of  the  back  ;  others  are  attached  to  one  arid 
then  another  of  these  little  bones  ;  and  others  still  are  attached 
to  the  ribs  and  to  the  back-bone.  All  these  serve  to  bend  the 
back  to  one  or  the  other  side,  and  forward  or  backward. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  311 

The  uppermost  bend  the  head.     They-serve  also  to  keep  the 
head  and  the  back  in  their  erect  position. 

717.  The  muscles  on  the  opposite  sides  of  the  spine  are 
naturally  of  the  same  size  and  length,  and  equally  strong. 
They  give  to  each  side  of  the  back  the  same  support,  so  long 
as  they   are  accustomed  to  the  same   amount  of  exertion. 
But  if  we  allow  the  back  to  bend  to  one  side,  the  muscles 
within  the  curve  will  be  shortened,  and  those  on  the  outside 
will  be  lengthened.     The  muscular  action  is  then  increased 
on  the  convex,  and  diminished  on  the  concave  side ;    for  the 
muscles  on  the  outside  of  the  arch  are  obliged  to  exert  a 
constant  and  much  greater  force  to  prevent  the  further  curv- 
ing of  the  spine  than  was  necessary  merely  to  keep  it  bal- 
anced   in    the   erect   position ;    while   very   little  action   is 
required  of  those  which  are  on  the  opposite  side  and  within 
the  curve. 

718.  The  structure  of  the  back-bone  gives  it  great  strength 
as  well  as  flexibility.     Being  composed  of  alternate  bones  and 
cartilage,  and  held  together  by  strong  ligaments  and  supported 
by  many  muscles,  it  is  capable  of  bearing  great  burdens. 
All  the  upper  parts  of  the  body,  more  than  half  of  its  weight, 
and  all  the  burdens  that  we  carry  on  the  head,  the  shoulders, 
the  back,  and  the  arms,  rest  upon  it.     Porters  who  are  long 
trained  to  their  business  will  carry  upon  'their  shoulders',  or 
upon  their  heads,  a  burden  of  some  hundreds  of  pounds.    The 
Turkish  porters  in  Smyrna,  Asia  Minor,  carry  e:iormous  loads 
on  their  backs.     A  friend  who  has  been  there  writes  to  me, 
uThe  porters  in  Smyrna  have  a  pack  on  their  backs,  about 
twenty  inches  wide,  flat  on  the  outside,  so  that  the  load  lies 
on  it  steady  without  fastening.     I  saw  one  take;  a  box  of  Ha- 
vana sugar  on  his  back,  to  carry  from  the  boat  up  to  the 
warehouse,   a   short   distance  from   the   water.     The   sugar 
weighed  four  hundred  and  fifty  pounds,  or  more.     Captain  N. 
of  the  navy  said  to  him,  '  You  had  better  add  a  bag  of  coffee,' 
which  weighed  one  hundred  and  thirty  pounds.     The  porter 
said,  '  Put  it  on,'  which  he  did.     He,  the  porter,  then  turned 


312  PHYSIOLOGY    AND    HEALTH. 

to  Captain  N.,  and  said, '  If  you  will  give  me  a  dollar,  I  will 
carry  you  on  the  top  of  these.'  " 

719.  I  once  saw,  in  the  streets  of  Louisville,  Kentucky,  a 
colored  woman  carrying  a  tub  of  water  upon  her  head,  and  a 
pail  of  water  in  each  hand.     There  it  was  not  unfrequent  to 
meet  a  woman  with  a  large  pail  of  water  on  her  head,  which 
she  carried  with   apparent  ease  and  without  spilling.     We 
often  meet  the  Italian  pedlers  carrying  a  large  tray  covered 
with  images,  or  flower-pots,  or  toys,  upon  the  head.     They 
carry  this  with  as  much  apparent  security  as  others  would 
carry  them  in  their  arms.     Those  who  bear  upon  their  heads 
heavy  burdens  which  require  strength,  or  pails  of  water  that 
must  not  be  spilled,  or  fragile  merchandise  that  must  not 
be  broken,  carry  their  heads  very  erect  and  their  back-bones 
very  straight.     They  hold  the  upper  extremity  of  the  spine 
directly  over  the  lower  end. 

720.  This  perfectly  erect  position  of  the  spine  affords  the 
easiest  method  of  carrying,  not  only  burdens,  but  the  head 
and  the  trunk,  in  the  ordinary  walks  of  life.     Any  one  can 
try  the  experiment  of  holding  a  pole  erect  in  his  hand  by  one 
end.     If  it  be  vertically  erect,  he  will  exert  no  more  strength 
than  barely  to  lift  the  weight.     But  if  it  be  inclined  to  either 
side,  it  will  require  considerable  exertion  to  prevent  its  fall- 
ing.    So,  if  the  head  be  bowed  forward,  if  the  chest  be  bent 
downward,  then  the  weight  is  not  immediately  above  the  point 
of  support ;  it  does  not  rest  upon  this  foundation,  but  it  must 
be  held  up  by  the  exertion  of  the  muscles,  which  is  a  very 
wearisome  labor. 

721.  In  order  to  carry  the  head  and  body  with  the  greatest 
ease,  we  must  be  governed  by  the  same  law  as  in  carrying 
any  burdens.     We  must  bring  the  weight,  the  centre  of  its 
gravity,  perpendicularly  above  the  point  of  support.     But, 
if  we  have  any  weight  added  to  one  side  of  the  body,  we 
must  change  the  direction  of  the  spine,  so  that  it  shall  bring 
the  centre  of  weight  in  the  proper  line.     This  we  do  instinc- 
tively.    When  a  boy  carries  on  his  breast  an  armful  of  wood, 
he  Jeans  backward  to  bring  the  weight  over  the  base  of  the 


BONES,    MUSCLES,    EXERCISE,    AND    REST. 


313 


spine.  The  fat  man  with  large  abdomen  does  the  same,  and 
for  the  same  reason.  Otherwise  they  would  necessarily  exert 
great  force  of  the  muscles  of  the  back,  to  prevent  their  fall- 
ing forwards. 

722.  If  a  porter  stands  perfectly  erect  when  he  carries  a 
trunk  on  his  back,  (Fig.  LVIII.,)  the  line  of  gravitation  falls 
behind  his  natural  line  of  support,  and  tends  to  throw  him 
backwards.  To  prevent  this,  and  bring  the  burden  over 
the  point  of  support,  he  leans"  forward,  (Fig.  LIX.) 

Fm.  LVIH.  FIG.  LIX. 


For  the  same  reason,  the  hod-carrier  leans  to  the  left 
when  he  carries  his  burden  on  his  right  shoulder,  and  to 
the  right  when  he  bears  it  on  the  left  shoulder.  When 
a  boy  carries  a  heavy  pail  of  water  with  one  hand,  he  leans 
as  far  as  he  can  to  the  opposite  side ;  but,  as  he  does  not  lean 
far  enough  to  bring  the  centre  of  gravity  over  the  point  of 
support  without  spilling  the  water,  he  throws  out  the  other 
arm,  and  carries  it  in  a  horizontal  position,  to  create  a  greater 
weight  on  that  side,  and  balance  the  weight  of  water.  And 
often  he  finds  it  easier  to  divide  his  water  into  two  pails,  and, 
27 


314  PHYSIOLOGY    AND    HEALTH. 

by  carrying  one  in  each  hand,  brings  the  centre  of  weight 
over  the  point  of  support,  with  his  spine  perfectly  erect. 

723.  Upon  the  same  principle  of  carrying  the  centre  of 
gravity  over  the  centre  of  support,  every  one  should  carry  his 
head  erect  and  his  back-bone  straight.     It  is  not  necessary 
for  this  to  obliterate  the  natural   curves  of  the  spine,   but 
to  carry  its  line  of  support  vertical  from  its  base  to  the  top. 
This  will    bring  the   head  directly  over   the  lower  end  of 
the  spine.     In  this  attitude,  the  weight  of  the  head,  trunk, 
and  whatever  burdens    are  borne,  resting   upon  the  bones, 
very  little  muscular  action  is  required ;  and  the  bones  of  the 
lower  limbs,  and  the  general  course  of  the  spine,  are  in  the 
same  line.     When  these  bones  are  in  this  upright  direction, 
and  the  upper  balanced  upon  the  lower,  it  requires  but  little 
muscular  exertion  to  hold  them  in  their  places.     But  if  the 
lower  bones  are  turned,  or  the  spine  is  bent  to  either  side, 
it  requires  a  constant  exertion  of  the  muscles  on  the  convex 
side  of  the  joint  or  the   spine  to  prevent  it  from  bending 
farther.     Whatever  muscular  strength  is  expended  in  main- 
taining the  attitude,  cannot  be  devoted  to  any  other  purpose. 

724,  This  attitude,  is    not  only  the  easiest,  but    the  most 
graceful.     Stooping  the  body,  or  bending  the  head  forward, 
when  walking  or  standing,  interferes  with  the  elegant  flexi- 
bility of  the  spine,  and  is  awkward  and  uncomfortable  to  the 
person.     Among  those  who  carry  burdens  upon  their  heads 
we  find  the  most  frequent  instances  of  graceful  attitude  and 
gait.     Captain  Ball,  in  his  "  Seven  Years  in  Spain,"  says, 
"  It  is  wonderful  to  see  the  amazing  burdens  that  the  Spanish 
women  carry  on  their  heads,  and  walk  at  so  rapid  and  safe  a 
pace  without  the  least  accident.     It  is  remarkable  that  the 
female  peasantry  in  Spain  have  a  more  graceful  and  comely 
style  of  walking  than  the  ladies,  which  I  have  repeatedly 
heard  accounted  for  by  the  burdens  that  they  carry  on  their 
heads  requiring  a  certain  degree  of  steadiness  to  balance." 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  315 


CHAPTER  XIX. 

Erect  Attitude  best  for  Walking.  —  For  Labor.  —  For  Mechanics  and 
Farmers.  —  For  great  Exertions.  —  For  Speakers.  —  Spine  curves 
from  Front  to  Back.  —  Becomes  bent  by  much  stooping.  —  Position 
of  Students  and  Writers  raises  the  Shoulders  and  curves  the  Spine 
from  Side  to  Side.  —  Curved  Spine  frequent  among  Girls,  but  not 
among  Boys.  — Injures  Spinal  Cord. 

725.  "  In  walking,  it  is  all-important  that  the  body  be  held 
as  upright  as  possible,  the  shoulders  being  kept  back,  and 
the  breast   projected    somewhat  forward,  so  as  to  give  the 
chest  its  full  dimensions.     The  lungs  being,  by  this  means, 
allowed  sufficient  room  to  expand  fully,  breathing  is  rendered 
free  and  easy,  and  every  vital  action  is  performed  with  vigor. 
The  attitude  thus  assumed  in  walking,  places  all  the  organs 
of  the  body  in  their  most  natural  position,  and  frees  them 
from  all  constraint."  *  * 

726.  The  wielding  of  the  heavy  sledge  of  the  blacksmith, 
and  planing  of  the  hard  wood  of  the  wheelwright,  are  done 
with  comparative  ease  if  the  body  is  kept  erect.     Such  op- 
erations of  agriculture  as  hoeing,  mowing,  ploughing,   are 
generally  easiest  in  the  same  position.     Two  men  mowed 
side  by  side  during  a  summer.     One  of  these  men  was  rath- 
er  tall,   large,    and   very  muscular,    and   was   reputed   the 
strongest  man  in  his  town.     The  other  was  rather  under  the 
common  height,  of  slender  form,  but  very  active.     When 
mowing,  the  strongest  bent  his  body  down,   and  struck  his 
scythe  with  all  his  might.     The  other  stood  erect,  and,  with- 
out much  apparent  effort,  swung  his  scythe  as  one  swings  a 
cane.     These  two  men,  making  such  different   efforts,  per- 
formed equal  work  in  the  course  of  the  day.     But  when  they 
went,  home  at  night,  the  strong  man  was  wearied  and  almost 
exhausted ;  the  other  was  somewhat  fatigued,  but  lively  and 
elastic. 

*  Journal  of  Health,  Vol.  I.  p.  120 


316  PHYSIOLOGY   AND    HEALTH. 

727.  This   erect   position  is   particularly  attended  to  by 
those  who  wish  to  exert  the  most  effective  force,  and  to  strike 
the  heaviest  blows.     Soldiers,  who  endure  fatiguing  marches 
and  fight  with  the  greatest  energy,  are  especially  directed  to 
maintain  the  erect  attitude.     So  the  prize-fighters  are  taught 
to  stand  in  the  struggle;  their  back  is  straight,  their  shoul- 
ders thrown  back,  and  breast  forward ;  then  their  arms  are 
completely   under  their   control.     The    best   public  speak- 
ers and  readers  stand  in  the  same  position.     Their   chests 
are  free  to  expand,  and  they  inhale  large  portions  of  air;  the 
head  is  erect,  and  the  windpipe  is  not  compressed ;  then  the 
air  can  be  thrown  forcibly  from  the  lungs,  the  voice  is  full, 
and  the  articulation  easy  and  effective. 

728.  The  healthy  spine,  in  its  natural  position,  curves 
from  front  to  back  and  from  back  to  front,  but  not  from  side 
to  side.     When  left  to  itself,  it  assumes  this  shape ;  yet  its 
structure  of  alternate  bones  and  cartilages  allows  the  column 
a  great  variety  of  motions  and  positions;  but  the  elasticity  of 
the  cartilages  tends  tocestore  it  to  its  natural  direction,  after 
having  been  bent  to  either  side.     So  that,  after  leaning  and 
bending  the  spine  to  the  left  or  to  the  right,  by  force  of  the 
muscles,  when  these  cease  to  act,  the  side  of  the  cartilages 
which  was  flattened  springs  upward,  and  throws  the  spine 
again  into  its  natural  position.     But  if  the  column  be  turned 
to  one  side  frequently,  and  continued  for  a  long  period,  and  at 
the  same  time  be  pressed  down  by  a  weight,  the  compressed 
side  of  the  cartilage  wanting  opportunity  to  regain  its  usual 
form,  will  become  permanently  thinner,  and  the  opposite  side 
thicker;  and  then  the  whole  pile  would,  without  any  external 
aid,  remain  curved. 

729.  This  great  flexibility  of  the  spinal  column  allows  it 
to  bend  in  any  direction ,   and,  for  a  short  period,  without 
danger  of  permanent  curvature,  if  a/terwards  the  upright  pos- 
ture be  assumed  and  maintained.     But,  if  we  continue  these 
positions  for  a  long  time,  the  spine  does  not  easily  recover  its 
proper  shape.     If  the  student  bends  his  back  and  leans  his 
head  down,  to  bring  the  eyes  nearer  his  book,  if  the  seam- 


BONES,    MUSCLES,     EXERCISE,    AND    REST. 


317 


stress  bends  her  chest  forward  over  her  sewing,  or  if  the  erj- 
graver  or  watchmaker  has  his  bench  so  low  that  the  spine 
must  be  curved  forward  to  bring  himself  near  to  his  work, 
and  if  they  sit  in  this  manner  for  months  and  years,  the  car- 
tilages are  compressed  beyond  the  power  of  reaction.  The 
front  part  is  flattened  and  the  back  part  is  thickened  ;  it 
becomes  wedge-shaped,  and  consequently  the  back-bone  is 
permanently  crooked,  and  the  person  stoops  or  is  rourid- 
shouldered. 

730.  The  same  law  applies  to  the  lateral  line  of  the  back- 
bone, and  similar  habits  of  compression  of  the  cartilages 
bring  on  curvatures  from  side  to  side.  The  position  assumed 
at  school  while  writing,  (Fig.  LX.)  and  often  while  studying, 
throws  the  spine  out  of  its  straight,  lateral  line,  and  bends  it 
to  one  side  or  the  other.  The  table  or  desk  for  writing  or 
FIG.  LX.  Fm.  LXI. 


drawing  is  usually  higher  than  the  elbow,  as  it  hangs  from 
the  shoulders  of  the  pupil  sitting  on  the  seat.  In  order,  then, 
to  write  or  draw,  the  right  arm  and  elbow  are  raised  and  rested 
upon  the  elevated  table.  This  raises  the  right  shoulder,  and, 
in  raising  it,  bends  the  upper  part  of  the  spine  over  from 
the  right  to  the  left,  and  depresses  the  left  shoulder.  Then. 
27  * 


318  PHYSIOLOGY    AND    HEALTH. 

in  order  that  the  head  should  still  be  over  the  base  or  point 
of  support,  the  upper  curvature  is  balanced  by  an  opposite 
lower  curvature.  While  the  upper  part  of  the  spine  is  curved 
to  the  left,  the  lower  part,  at  the  loins,  is  curved  to  the  right, 
and  the  whole  column  assumes  somewhat  the  shape  of  the 
letter  S  in  its  lateral  direction.  At  the  same  time,  the  lowest 
and  the  highest  portions  are  nearly  straight,  and  the  head  is 
vertically  above  the  base  of  the  column.  (Fig.  LX.) 

731.  The  same  effect  follows  from  a  position  sometimes 
assumed  in  reading.     The  table  is  higher  than  the  suspended 
elbow,  and  the  reader  does  not  sit  directly  facing  it,  but 
rather  obliquely,  and,  lolling  sidewise,  raises  the  elbow  upon 
the  table,  and  rests  the  head  upon  the  hand.     This  raises  the 
shoulder,  bends  the  spine,  and  produces  the  same  result  that 
comes  from  the  unnatural  posture  in  writing  and  drawing. 
If  these  positions  are  frequently  changed,  if  one  shoulder  is 
raised  as  often  as  the  other,  and  neither  elevation  is  continued 
for  a  long  time,  no  curvature  of  the  spine  will  follow.     But 
if  either  bent  position  be  assumed  frequently,  and  maintained 
for  a  long  time,  the  cartilages  will  lose  their  elasticity,  and 
become  .compressed  on  one  side  and  expanded  on  the  other. 
In  the  natural  form,  the  shoulders  are  of  the  same  size;  they 
both  rest  upon  the  back  of  the  chest,  and  lie  upon  the  ribs, 
which  are  fixed  upon  the  spine.     If  we  examine  any  active 
boy,  or  any  playful,  healthy  girl,  we  shall  see  that  the  shoulders 
are  exactly  alike ;  they  are  of  the  same  height,  and  have  the 
same  shape.     But,  if  we  examine  many  girls  who  are  pursu- 
ing or  have  finished  their  education,  we  shall  find  that  one 
of  the  shoulders  is  grown  out,  and   is  higher,  and  projects 
farther  forward  than  the  other. 

732.  The  habits  of  school  children,  and  especially  of  girls, 
of  students,  clerks,  draughtsmen,  and  of  some  others,  create 
a  fearful   frequency  of  this  spinal   distortion.     Dr.  Warren 
says,  "  In  the  course  of  my  observation,  I  have  been  able  to 
satisfy  myself  that  about  half  the  young  females,  brought  up 
as  they  are  at  present,  (1845,)  undergo  some  veritable  and 
obvious  change  of  structure ;  and,  of  the  remainder,  a  large 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  319 

number  are  the  subjects  of  great  and  permanent  deviations; 
while  not  a  few  entirely  lose  their  health  from  the  manner  in 
which  they  are  reared."  And  again,  "  I  feel  warranted  in  the 
assertion,  already  intimated,  that  of  the  well-educated  females 
within  my  sphere  of  experience,  about  one  half  are  affected 
wit/i  some  degree  of  distortion  of  the  spine"*  Dr.  Warren 
substantiates  his  opinion  by  that  of  Lachaise,  a  French  author 
upon  the  spine,  who,  in  speaking  of  the  lateral  curvature, 
says,  "  It  is  so  common,  that,  out  of  twenty  young  girls  who 
have  attained  the  age  of  fifteen,  there  are  not  two  who  do  not 
present  very  manifest  traces  of  it."  A  fashionable  mantua- 
maker,  of  extensive  experience  and  observation,  says  that 
she  has  been  obliged  to  stuff  with  cotton  a  large  propor- 
tion of  the  ladies'  dresses,  on  one  side  or  the  other,  to  make 
them  exactly  symmetrical. 

733.  Nature  lias  given  to  all — to  both  female  and  male 
—  sufficiency  of  bone  and  muscle  to  sustain  tlum  in  the,  most 
graceful  and  healthy  position  ;  and  when  these  are  faithfully 
used,  and  their  strength  developed,  they  fulfil  their  purposes, 
and  keep  the  form  straight.  The  lateral  curvature  of  the 
spine  is  very  rarely  found  among  boys.  Their  various  and 
free  exercise  strengthens  all  their  muscles,  and  prevents  it. 
But  it  is  very  common  among  females,  who  exercise  less,  and 
wear  external  supports,  which  are  intended  to  take  the  place 
of  their  natural  framework  and  muscular  power,  and  sustain 
the  body.  But  these  substitutes  not  only  fail  of  their  pur- 
pose, but  sometimes  bring  on  the  very  deformity  they  were 
intended  to  prevent.  Although  nature  has  provided  all  the 
•proper  supports  for  the  spine,  yet,  when  they  are  not  used, 
they  become  weak,  and  then  the  spine  bends  to  one  side. 
This  lateral  deformity  is  rarely  found  among  laborious  farm- 
ers or  mechanics  employed  in  the  heavy  trades,  or  among 
porters,  or  even  hod-carriers,  who  carry  heavy  burdens  on 
their  shoulders  or  heads,  but  in  sedentary  persons,  who  lift 
the  least,  and  whose  work  is  the  lightest,  the  muscles  of 
*  Preservation  of  Health,  p.  13. 


320  PHYSIOLOGY    AND    HEALTH. 

whose  backs  have  no  other  employment  than  to  hold  the 
spine  erect. 

734.  The  curvature  of  the  spine  not  only  injures  the  sym- 
metry of  the  frame  and  lessens  its  height,  but  it  distorts  the 
chest  and  diminishes  its  capacity,  and  interferes  with  the  free 
motions  of  the  ribs.     Accordingly,  the  lungs  have  less  space 
for  rest  and  less  room  for  expansion,  and  therefore  can  re- 
ceive less  air  at  each  inspiration;  then,  imperfect  purification 
of  the  blood,   and,  lastly,  a  deficient  nutrition  of  the  body, 
must  necessarily  follow.     Sometimes  serious  diseases  of  the 
lungs  are  brought  on   by  this  curvature  of  the  spine,  and 
Dr.  Hope  says,  "  The  majority  of  hump-backed  persons  are 
ultimately  attacked  by  disease  of  the  heart." 

735.  The  rings  in  the  vertebrae  (Fig.  XXXIV.)  being  placed 
one  upon  another,  form  a  channel  or  tube  through  the  whole 
spinal  column.     This  channel  is  of  the  utmost  importance  in 
the  animal  structure,  for  it  encloses  the  great  nerve  called 
the  spinal  marrow,  that  extends  from  the  brain  to  the  trunk 
and  the  lower  part  of  the. system,  and  supplies  all  these  parts 
with  the  principle  of  life.     This  great  nerve  begins  in  the 
brain,  and  reaches  to  the  end  of  the  spinal  column.     In  the 
course  of  its  descent,  it  sends  out  on  each  side  nerves  to  the 
heart  and  lungs,  to  the  organs  of  digestion  and  of  motion. 
All  the  parts,  therefore,  of  the  trunk  and  all  the  extremities 
depend,  more  or  less,  upon  the  healthy  condition  of  this  great 
nerve  for  their  fulness  of  life  and  freedom  and  energy  of 
action. 

736.  Any  change  in  the  shape  of  the  spinal  column,  or  in 
the  relations  of  these  bones  to  each  other,  must  diminish  the 
capacity  of  this  canal,  and,  of  course,  press  somewhat  upon 
this  great  nerve.   This  pressure  upon  this  nerve  interrupts  its 
freedom  of  action,  and  interferes  with  the  communication 
between  the  brain  and  the  parts  of  the  body  which  receive 
nerves  through  this  channel.     This  must  be  the  natural  con- 
sequence of  all  distortions  of  the  spine,  all  permanent  curva- 
tures from  side  to  side,  and  of  all  unnatural  curvatures  from 
front  to  back,  or  from  back  to  front. 


BONES,    MUSCLES,    EXERCISE,    AND    REST.  321 


CHAPTER    XX. 

Day  is  Time  for  Labor.  —  Experiments.  —  Soldiers.  — Miller.  —  Sleep. 
—  Quantity  of  Sleep.  —  Night  proper  Time  for  Sleep.  —  Deficient 
Sleep  causes  Weakness.  —  Circulation  feeble,  and  Pleat  less  in 
Sleep.  —  Difficult  Digestion  disturbs  Sleep. 

737.  The  day  is  the  time  for  labor,  and  the  night  is  the 
time  for  rest.    This  seems  to  be  the  almost  universal  law  of 
nature.    During  the  light  of  day,  the  air  is  more  pure,  and 
respiration  is  better  sustained,  the  changes  of  particles  are 
more  easy,  and  consequently  the  muscles  are  better  strength- 
ened.    The  light  of  the  sun  has,  in  some  way  or  other,  a 
great  influence  upon  the  energies  of  the  body  and  the  mind. 
The  effect  of  a  long  series  of  cloudy  days  upon  the  spirits 
is  familiar  to  all ;  we  then  become  dull  and  querulous  about 
the    weather,   and   the  return    of  the    sunshine   is  received 
with  a  burst  of  joy,  as  if  it  brought  back  new  life.     Miners, 
who  spend  most  of  their  daytime  within  the  earth,  become 
bleached  and  dull.     Mechanics  and  shopmen,  who  work  or 
transact  business  in  imperfectly-lighted  shops,  have  a  lower 
degree  of  energy  and  health. 

738.  Night  labor  is  attended  with  the  double  disadvantage 
of  bad  air  and  darkness.     The  evil  consequences  of  this  were 
shown  in  the  experiment  of  two  French  regiments.     "  One 
of  them,  although  it  was  in  the  heat  of  summer,  marched  in 
the  day  and  rested  at  night,  and  arrived  at  the  end  of  a  march 
of  600  miles  without  the  loss  of  either  men  or  horses ;  but 
the  other,  who  thought  it  would  be  less  fatiguing  to  march 
in  the  cool  of  the  evening,  and  part  of  the  night,  than  in  the 
heat  of  the  day,  at  the  end  of  the  same  march  had  lost  most 
of  the  horses  and  some  of  the  men."  * 

739.  A  similar  experiment  is  partially  tried  by  individuals, 
almost  every  where,  with  the  same  success.     Milkmen  and 

*  Art  of  Living  Long  and  Comfortable,  p.  172. 


322  PHYSIOLOGY    AND    HEALTH. 

market-men  in  the  neighborhood  of  cities,  and  workmen  in 
tide-mills,  spend  a  part  of  the  night  in  their  business,  and 
make  up  their  loss  of  sleep  in  the  day ;  but  in  a  few  years  they 
are  very  glad  to  discontinue  this  course,  and  confine  themselves 
to  daylight  labor.  Mr.  G.  owned  and  worked  a  tide-mill,  which 
could  run  only  for  a  few  hours  succeeding  a  full  tide,  which 
came  as  often  in  the  night  as  in  the  day.  In  course  of  a  few 
years,  this  frequent  night  work  wore  so  much  upon  him  as  to 
compel  him  to  exchange  his  tide-water  power  for  steam 
power,  which  he  could  use  to  suit  his  own  convenience. 
Having  given  up  night  work,  and  limited  his  labor  to  the 
day,  from  a  feeble  he  has  become  a  robust  man,  and  is  able 
to  accomplish  more  in  the  new  than  in  the  old  system. 

740.  It  is  a  law  of  nature  that  all  animals  shall  suspend 
their  actions,  and  sleep.     The  alternations  of  day  and  night 
harmonize  with  this  want  of  the  living  animal  body,  and 
afford  seasons  of  activity  and  of  rest.     Man  needs  to  follow 
this  natural  indication,  and  alternate  his  sleep  and  wakeful- 
ness  daily.     Sleep  is  nature's  restorer  of  exhausted  power, 
and,   though  we  retire  wearied,   we    awake   refreshed    and 
strong;  the  expended  energies  are  recovered,  the  strength 
brought  back,  and  we  are  again  ready  for   action.     In  the 
state  of  sleep,  all  motion  of  the  voluntary  muscles  is  stayed, 
and  the  brain  suspends  its  active  functions ;  but  the  invol- 
untary functions  go  on  as  when  awake;    the  chest  moves, 
the  lungs  breathe,  and  the  blood  is  purified,  the  heart  beats, 
the  blood  circulates,  and  the  system  is  nourished. 

741.  The  quantity  of  sleep  that  is  necessary  is  varied  by 
,so  many  circumstances,  that  no  rule  can  be  established  for 
all.     The  time  of  life  and  the  peculiarities  of  constitution 
make  a  difference.     The  sluggish  and   the  lymphatic  need 
more  sleep  than  the  active  and  the  nervous.     Some  sleep  very 
much,  and  are  not  refreshed,  nor  ready  for  action,  if  they 
are  deprived  of  their  usual  quantity  of  rest.     Others  take 
very  little  sleep,  and  cannot  obtain  more.     Without  giving 
any  precise  rule,  it  is  sufficient  to  say  that  men  and  women 
who  have  arrived  at  .adult    years,  and    developed  their  full 


BONES,    MUSCLES,    EX 

strength,  need  from  seven  to  nine 

of  sleeping  create  a  difference  of  necessity^Tor  a  time  at 

least,  and  cannot  easily  and  suddenly  be  broken. 

742.  The  sleep  in  the  day  does  not  compensate  for  the 
loss  of  the  niyht  sleep.     The  soldiers  who  rested  in  the  day, 
and  marched  at  night,  had  as  much  sleep  as  the  others,  who 
slept  at  night ;  and  yet  they  suffered  much  more  from  sick- 
ness and  exhaustion.  (§  738,  p.  321  )     The  most  perfect  sleep 
and  refreshing  rest  is  obtained  in  the  stillness  of  darkness, 
when  all  nature  reposes ;  and  it  is  all  in  vain  that  any  one 
struggles  against  this  law  of  his  being.     He  may  sleep  in  the 
day,  and  labor  or  watch  in  the  night,  but  his  waking  hours 
are  then  not  so  bright,  nor  is  his  energy  of  life  so  great,  as 
otherwise  it  would  be. 

743.  There  are  few  who  do  not,  now  and  then,  devote  a 
night,  or  a  part  of  a  night,  to  some  labor,  to  travel,  to  parties  of 
pleasure,  or  to  watching  with  the  sick.     None  of  these  escape 
the  penalties  that  always  follow  the  violation  of  the  law  of 
rest.     Whatever  may  be  the  time  required  by  habit,  or  the 
constitution,   for  sleeping,  for  the  recovering  of  exhausted 
power,  that  time  cannot  be  shortened  without  impairing,  in 
some   measure,  the  strength   and   activity  of  the  next  day. 
With  less  than  the  required  quantity  of  sleep,  the  body  is  not 
completely  refreshed,  nor  has  it  the  full  energy  for  action. 
If  each  day  is  expected  to  accomplish  its  entire  work,  each 
night  must   have  its  complete  rest;  and  whatever  is  taken 
from  the  sleep  must  be  taken  from  the  power  of  labor.     If 
any  one  cannot  retire  at  his  accustomed  hour,  and  still  wishes 
to  have  his  usual  power  of  action  on  the  next  day,  he  must 
protract  his  rest  in  the  morning  as  much  as  it  was  shortened 
at  night. 

744.  During  sleep,  the  circulation  is  more  feeble,  the  res- 
piration is  slower,  and  the  heat  is  generated  less  rapidly  than 
in  waking  hours,  (§  436,  p.  187,)  and,  consequently,  we  are 
less  able  to  resist  the  effects  of 'cold;  and  if  they  exposed  to 
a  current  of  air,  we  are  more  liable  to  suffer  than  when  we 
are  awake,     We  therefore  sleep  under  more  clothing  in  the 


324  PHYSIOLOGY    AND    HEALTH. 

night  than  we  wear  about  the  business  of  the  day.  If  pos- 
sible, one  should  not  go  to  bed  cold,  for  it  is  difficult,  when 
sleeping,  to  recover  the  heat  that  has  been  lost. 

745.  Sleep  is  the  most  refreshing  when  taken  in  large  and 
airy  chambers.     These  rooms  should,  therefore,  be  ventilated 
daily,  and  at  all  seasons,  by  opening  the  windows,  or  other- 
wise.    The  lodging-rooms  should  never  be  used  for  any  other 
purpose  —  for  sitting,  working,  cooking,  or  eating.     The  bed 
and  bedding  should  be  opened  and  thoroughly  aired  every 
day.     A  very  hard  bed  affords  but  few  points  of  support  for 
the  body,  which  is,  therefore,  not  so  well  rested  while  lying 
upon  it.     A  very  soft,  downy  bed  allows  the   body  to  sink 
within  it,  and  keeps  up  too  great  a  heat,  and  debilitates  rather 
than  strengthens  the  sleeper. 

746.  Nutrition  goes  on  during  sleep.     But  the  food  should 
be  digested  before  retiring  to  rest.  (§  121,  p.  59.)     Sleep  is 
disturbed  with  unpleasant  dreams  after  a  late  or  indigestible 
supper.     The  stomach  works  with  difficulty,  and  the  man 
dreams  of  being  in  difficult  situations,  or  of  attempting  pur- 
poses which  he  cannot  accomplish ;   still  greater  oppression 
at  the  stomach  produces  distressing  dreams  and  nightmare ; 
and  in  neither  case  is  the  natural  and  complete  refreshment 
obtained  from  the  sleep. 


BRAIN    AND    NERVOUS    SYSTEM. 


325 


PART    VII. 
BKA1N  AND   NERVOUS   SYSTEM. 


CHAPTER   I 

Nervous  System. —  Coverings  of  Brain. —  Spinal  Cord.  —  Nerves  of 
Sensation  and  Motion. — Distribution. 

747.  The  nervous  system  consists  of  the  brain,  the  spinal 
cord)  and  the  tierces.  The  brain  is  in4he  head  :  its  size  and 
shape  correspond  to  the  size  and  shape  of  the  skull.  Its  ex- 
ternal surface  is  not  smooth  and  level,  but  it  is  broken  into 

FIG.  LXII.    Brain.    External  Surface. 


a,  Right  lobe.  b,  Left  lobe.  c,  c,  Division  of  the  lobes. 

various  parts  called  convolutions,  giving  <he.  organ  the  appear- 
ance of  a  collection  of  small  lobes,  with  depressions  between 
them,  (Fig.  LXII.)  The  substance  of  the  brain  is  soft  and 

28 


326  PHYSIOLOGY    AND    HEALTH. 

somewhat  pulpy;  it  is  of  very  delicate  texture,  and  can  be 
easily  separated  by  the  fingers.  The  outer  portion  is  of  a  gray 
color,  and  is  called  the  cortical  part.  The  inner  portion  is  of  a 
white  color,  and  called  the  medullary  part. 

It  is  supposed,  by  somevthat  these  two  parts  of  the  brain 
have  different  offices ;  that  one  is  the  organ  of  the  mental 
operations  and  the  affections ;  that,  through  it,  the  mind  acts 
and  the  feelings  operate,  while  the  other  is  supposed  to  be 
the  organ  of  sensibility,  and,  upon  that,  impressions  from  the 
sensory  nerves  are  recejved,  and  in  it  sensations  are  created 
and  perception  takes  place,  and  that  it  holds  the  commu- 
nication with  all  the  rest  of  the  body.  But  how  far  this  sup- 
position is  true  is  not  shown,  nor  is  it  necessary  for  us  to  know. 

748.  The  brain  is  covered  and  held  together  by  three  mem- 
branes.    The  inner  and  the  middle  of  these  membranes  are 
very  delicate,  and  give  the  brain  a  sofUcushion  to  lie  between 
it  and  its  bony  enclosure.     The  outer  membrane  is  thick  and 
very  strong,  and  would  hold  the  brain  in  its  position   and 
retain  its  shape  even  when  removed  from  the  skull.     These 
membranes  surround,  the  brain  on ,  all  its  sides,  above  and 
below.     The  inner  and  soft  menabranes  dip. into  the  brain 
between  the  convolutions  or  little  lobes,  and  separate  them 
superficially. 

The  brain  is  divided  into  two  parts,  called  the  right  and 
left  lobes,  (Fig.  LXII.  a,  b,)  which  are  exactly  alike  on  the 
two  sides.  These  are  separated  by  a  partition  wall?or  a  wing 
(Fig.  LXII.  c,  c)  of  the  same  membranes  that  cover  the  organ. 
This  partition  runs,  from  the -front  to  the  back  of  the  skull, 
and  almost  to  the  bottom  of  the  brain.  It  supports  the  two 
lobes  in  their  position,  and  prevents-them  from  pressing  upon 
each  other  when  we  lie  down. 

749.  The  brain  is  also  divided  into  two  other  parts  —  the 
greater  or  cerebrum,  and  the  lesser  or  cerebellum.    The  greater 
occupies  almost  the  whole  of  the  cavity  of  the  head  above 
and  in  front.     The  lesser  is  behind  arid4jelow,  just  above  the 
neck.     A  wing  of  the  membran^g  extends  across  the  skull 
from  side  to  side  behind,  and  separates  these  two.  parts  of  the 


BRAIN    AND    NERVOUS    SYSTEM. 


327 


brain.  This  wing  is  attached  to  tke  bone,  and  gives  support 
to  the  brain,  and  protects  it  from  the  injury  that  might  come 
from  jars ;  and  it  also  prevents  the  upper  and  larger  organ 
from  pressing  upon  the  smaller  organ  below. 

750.  The  spinal  cord  extends  from  the          FIG.  LXIII. 
brain  through  ihe  whole   length  of  the      Brai®  and  Cord, 
back-bone,  (Fig.  LXIII.  6.)  In  the  bottom 

of  the  skull  there  is  a  large  hole,  which 
is  placed  directly  over,  and  opens  into, 
the  channel  in  the  spine.  This  channel 
is  formed  by  the  rings  of  the  successive 
vertebrae.  It  is  closed  on  all  its  sides, 
and  gives  a  sufficient  and  secure  place 
for  this  great  nerve  or  extension  of  the 
brain.  This  spinal  cord  is  composed  of 
pulpy,  nervous  matter,  like  that  of  the 
brain,  and  is  protected  by  the  same  deli- 
cate and  strong  membranes  that  cover 
the  organ  above. 

751.  The  brain   sends    nerves    to   the 
wlia1!'  body.     There  are  holes  in  the  base 
of  the  skuil  through  which  twelve  pairs 
pass  outward.     These  are  alike  on  the 
two  sides.     The  optic  nerves  pass  for- 
ward to  the  eyes.     The  auditory  nerves 
pass  sidewise  to  the  ears.     The  others 
pass  through  other  holes  to  the  fafce,  and 
to  some  other  parts  of  the  body.     Twelve 
pairs  go  directly  from  the  brain,  (Fig. 
LXIII.  a,)  and  thirty  pairs  go  from  the 
spinal  cord,  (Fig.  LXIII.  <•,  <•,  c.)     These 
nerves   divide   and  multiply  until    their 
branches  reach  every  part  of  the  body, 
and  every  organ,  muscle,  and  blood-ves- 
sel is  connected  with  the  brain  by  its  appropriate  nerve.    The 
nerve  of  the  face  passes  out  from  the  skull  below  the  ear, 
(Fig.  LXIV.  «,)  and  sends  its  branches  and  filaments  over  the 


a,  Brain. 

b,  Spinal  cord. 

c,  c,  c,  c,   Roots  of 
spinal  nerves. 


323  PHYSIOLOGY  AND  HEALTH. 

whole  face.     Other  nerves  are  in  like  manner  spread  over  the 
neck,  (Fig.  LXIV.  e,)  the  arm,  and  every  part  of  the  body. 

FIG.  LXIV.    Nerves  of  the  Face  and  Neck. 


a,  5,  Nerve  of  the  face.  d,  Nerve  of  the  forehead. 

752.  Two  kinds  of  nerves  extend  from  the  brain  and  spinal 
cord  to  the  body — those  of  sense  and  sensibility,  called  sen- 
sory  nerves  ;  and  those  of  motion,  called  motory  nerves.  The 
sensory  nerves  receive  the  external  impressions,  and  convey 
them  to  the  brain.  This  class  includes  -both  the  nerves  of 
special  sense, -as  the  optic,  auditory,  gustatory,  and  olfactory 
nerves,  which  go  to  the  eye,  ear,  tongue,  and  nose,  and  also 
the  nerves  of  general  sensibility,  by  which  we  feel  pleasure 
and  pain,  heat  and  cold.  The  motory  nerves  convey  from 
the  brain  to  the  muscukr  texture  the  stimulus  of  motion. 
The  muscles  are  supplied  with  both  classes  of  nerves,  and, 
therefore,  have  both  the  feeling  and  motory  power. 

75»3.    These  two  kinds  of  nerves  —  the  motory  and  sensory  — 


BRAIN    AND    NERVOUS     SYSTEM. 


329 


perform  separate  offices  ;  each  effects  its  own  purpose,  and  no 
more;  and  each  one  neither  interferes  with,  nor  can  take  the 
place  of,  the  other.  If,  from  any  cause,  the  nerve  of  motion 
alone  is  disordered,  ^separated,  or  pressed,  the  muscles  cannot 
move,  but  the  power  of  feeling  remains.  But  if  the  other 
nerve  —  that  of  sensibility  —  is  injured,  there  is  no  feeling,  but. 
a  power  of  motion.  If  the  motory  nerve  that  connects  the 
brain  with  the  muscles  of  the  jaw  and  lips  is  divided  in  any 
animal,  he  may  still  smell  his  food  with  his  nostrils,  and  feel  it 
with  his  lips,  but  he  cannot  open  his  mouth  to  take  it  in  and 
masticate  it.  But  if  the  sensory  nerve  is  divided,  the  animal 
cannot  feel  the  food  with  his  lips,  although  he  can  move  them 
to  take  it  in. 

754.    These  nerves  have  separate  roots  in  the  spinal  cord; 


FIG.   LXV. 

Section  of  the  Spinal  Cord. 

a 


the  sensory  nerve  arises  in  the 

posterior,  (Fig.  LXV.~d,r/,c?,rf,) 

and  the  motory  nerve  in  the  an- 

terior part.-  (e,e,e,e.)     These 

nerves    are    united    (c,  c,  c,  c,) 

soon  after  they  leave  the  spine, 

and  a"re  for  some  distance  in- 

cluded in  the  same  sheath,  yet 

their  branches  are  not  equally 

distributed  to   all   the  parts  of  c 

the  system.     The  skin  has  no 

power    of  motion,    but    it    has         a,  b.  Section  of  the  cord. 

great  sensibility.     It  is,  there-        c,  c,c,c.  Spinal  nerves. 

°  ~  »•<••!  d.d,d,d.  Posterior  or  sensory 

fore,  very  largely  supplied  with    roots  of  the  spin>al  nerves> 

sensory    nerves,    but    not    with         e,  e,  e,  e.  Anterior  or  motory  roots 
motory  nerves.     On^the  other    of  the  sPinal  nerves- 
hand,  the  muscles,   being  exclusively  organs  of  motion,  are 
very  largely  endowed  with  motory  nerves,  but  with  a  limited 
supply  of  the  sensory  fibres.     In  consequence  of  this,  when 
the  surgeon  amputates  a  limb,  great  pain  is  suffered  while  the 
knife  is  cutting  through  the  skin,  and  comparatively  little 
when  the  muscles  are  divided. 
28* 


330  PHYSIOLOGY    AND    HEALTH. 


CHAPTER    II. 

Sensation  is  in  Brain.  —  Produced  by  Impressions  on  outer  Ends  of 
Nerves,  and  carried  on  Nerve  to  Brain.  — No  Sejisibility  nor  Power 
of  Motion  in  Part  which  does  not  communicate  with  Brain. — 
Cutting  Nerve,  or  Pressure  on  Nerve,  paralyzes  Parts  to  which  it  is 
distributed.  —  Foot  asleep. — ,  Injury^ of  Spinal  Cord  paralyzes  Parts 
below. 

755.  SENSORY  nerves  carry  impressions  from  their  outer 
extremities  in  the  organs  of  sense,  and  in  the  flesh,  to  their 
ends  in  the  brain,  where  the  sensation  is  excited.     The  trunk 
of  the  healthy  nerve  has  no  feeling,  and  receives  no  impres- 
sions ;  it  is  merely  a  messenger  to  carry  the  impressions  from 
the  points  where  they  are  made,  to  the  brain,  where  they  are 
recognized.     Sensation  is  not  in  the  outer  end  of  the  nerve, 
nor  in  its  trunk,  but  in  the  brain,  at  the  inner  end  of  the 
nerve.     There  are,  then,  three  things  in  this  work  of  sensa- 
tion :   1st,  the  extremity  of  the  nerve,  which  first  receives  the 
impression ;  2d,  the  brain,  which  perceives  the  impression ; 
and,  3d,  the  connecting  line  of  nerve    between  them ;  and 
if  either  of  these  be  wanting,  or  injured,  there  can  b£  no 
healthy  sensation.     The  power  of  motion  requires  the  same 
three  things  —  the  brain,  through  which  the  rnind  determines 
or  wills  the  motion ;  the  nerve,  to  carry  this  volition  or  di- 
rectipn  to  the  muscle ;   and  the  nervous  termination,  which 
imparts  the  stimulus  to  the  moving  texture. 

756.  The  power  of  motion,  and  the  sensibility  of  any  part, 
require  this  constant  and  uninterrupted  nervous  communica- 
tion with  the  brain. ;  and  if,  from  any  cause,  this  connection  be 
suspended, —  if  any  nerve  be  cut,  or  divided,  or  pressed,  —  the 
power  both  of  motion  and  of  feeling  is  destroyed,  or  im- 
paired, in  the  part  where  the  nerve  terminates.     The  familiar 
circumstance  of  the  foot  being  asleep  is  caused  by  the  pres- 
sure upon  the  nerves  that  lead  down  the  leg  to  this  extremity. 
The  communication  between  the  terminations  of  the  nerves 
below  and  the  brain  above  is  thus  interrupted,  and  then  the 


BRAIN    AND    NERVOUS    SYSTEM.         .  331 

foot  can  neither  feel  nor  move.  In  this  state  we  try  in  vain 
to  walk,  for  the  muscles  cannot  act ;  and  if  we  strike  the 
foot,  we  feel  no  pain ;  but  when  the  pressure  is  removed,  and 
the  communication  restored,  sensibility  returns  to  the  foot, 
and  the  power  of  contraction  to  the  muscles. 

757.  Most  of  the  nerves  of  sensation  and  of  motion  do  not 
pass  directly  from  the  brain  to  the  trunk  and  the  extremities,  but 
from  the  spinal  cord.  (Fig  LXV.  e,  e,  c,  e.)  The  upper  part  of  the 
cord  sends  nerves  to  the  arms,  and  to  the  chest  and  its  organs, 
the  heart  and  the  lungs.     The  middle  part  supplies  the  ab- 
domen, and  the  lower  part  supplies  the  lower  limbs.     These 
several  organs  and  parts  of  the  body  hold  their  communica- 
tion with,   and  receive  their  nervous  life   from,  the  brain, 
through  this  nerve,  or  rather  bundle  of  nerves,  in  the  back- 
bone, and  the  branches  which  pass  from  it. 

758.  There  are  thirty  pairs  of  nerves,  or  branches,  which 
.go  from  tliis  cord  to  the  body  and  the  limbs.     These  parts 
must  not  only  have   free  nervous  connection  with  the  spinal 
cord,  but,  through  the  cord,  they  must  have  uninterrupted 
communication  with  the  brain.     If  this  communication  be 
interrupted  or  broken  off  in  the  cord,  all  the  parts  of  the 
body  which  are  supplied  with  nerves  from  it,  below  the  point 
of  obstruction,  will  be  deprived  of  their  power  of  sensation 
and  motion.     This  palsy  of  the  muscles  or  parts  of  the  body, 
and  interruption   of  the  regular  operatipns  of  the  organs, 
happen  occasionally  from  such  accidents  to  the  spine  as  pro- 
duce pressure  upon  its  great  nerve,  and  sometimes  from  dis- 
tortion, or  curvature,  which,  in  a  lesser  degree,  produce  the 
same  effect  upon  the  cord. 

759.  Mr.  J.  fell,  in  the  year  1830,  and  struck  the  hollow 
of  his  back  on  some  stones,  and  injured  the  spine  about  the 
middle  of  the  back.     The  cord  was  injured  or  pressed  at  that 
point,  and  free  communication  between  the  lower  parts  of  the 
cord  and  the  brain  interrupted.     All  the  parts  of  the  body 
below  the  injury  were  palsied.     But  the  power  of  motion  and 
of  sensation  was  restored  as  the  cord  recovered   from  the 
effects  of  the  accident,  and'  the  pressure  was  removed,  or  the 


332  PHYSIOLOGY    AND    HEALTH.  ' 

injury  healed.  In  another  case,  the  paralysis  was  more  ex- 
tensive, having  been  produced  by  an  injury  at  the  lower  part 
of  the  neck.  There  was,  at  first,  a  total  loss  of  voluntary 
power  over  the  lower  extremities,  trunk,  and  hands,  slight 
remaining  voluntary  power  in  the  wrists,  rather  more  in  the 
elbows,  and  still  more  in  the  shoulders.  The  muscles  of  the 
ribs  were  also  paralyzed,  and  the  breathing  was  carried  on 
entirely  by  means  of  the  diaphragm.*  If  the  injury,  in  the 
last  case,  had  been  higher  in  the  neck,  above  the  origin  of 
the  nerve  which  leads  to  the  diaphragm,  this  muscle  also 
would  have  been  paralyzed,  and  death  would  instantly  have 
taken  place,  for  want  of  power  of  respiration. 

760.  The  higher  any  injury  occurs  to  the  spinal  cord,  the 
more  extensive  must  be  the  bad  consequences;  that  is,  the 
nearer  the  root  the  interruption  happens,  the  greater  num- 
ber of  its  branches  must  be  affected.     An  injury,  or  a  curva- 
ture, may  cause  pressure  upon  the  whole  or  a  part  of  this 
nerve,  or  upon  a  part  of  its  branches  only,  and  thus  interrupt 
or  interfere  with  the  communication  between  the  brain  and 
the  organs  to  which  these  branches  lead.     In  this  way  the 
lungs  and  the  stomach  are  sometimes  disturbed  or  enfeebled, 
and  difficulty  of  breathing  or  dyspepsia  produced. 

761.  At  first,  Mr.  J.  (§  759,  p.  329)  suffered  great  pain 
and  palsy  of  the  lower  limbs.     But  the  injury  was  not  per- 
manent; the  pressure  on  the  cord  was  gradually  and  slowly 
removed,  the  pain  was  relieved  in  all  the  parts,  and  the  power 
of  motion  returned  to  the  muscles  successively ;  and,  finally, 
he  regained  the  use  of  all  his  muscles,  except  those  which 
lift  the  feet.     These  were  palsied  and  useless  to  him  ;   and 
during  the  twenty-five  remaining  years  of  his  life,  though 
he  could  move  his  thighs  and  legs,  and  press  his  feet  down- 
ward, he  could  not  bend  them  upward  on  the  ankle ;   and 
when  he  walked,  the  foot  hung  down,  and  the  toes  struck 
the  ground  first,  instead  of  the  heel.     Probably  a  fibre  or 
branch  of  the  motory  nerve,  that  leads  to  the  muscles  which 
bend  the  ankle,  was  injured  beyond  recovery. 

*  Carpenter's  Physiology,  §  178. 


BRAIN    AND    NERVOUS    SYSTEM.  333 

762.  It  is  not  to  be  presumed  that  the -pressure  upon  the 
spinal  marrow,  from  a  curvature  or  distortion  of  the  spine, 
will  produce  so  sudden  or  perceptible  injury  as  Mr.  J.  suf- 
fered ;  but  his  case  illustrates  the  connection  between  the  con- 
dition of  the  spinal  marrow  and  the  health  and  power  of  the 
organs  and  systems  which  derive  their  nerves  from  it.  These 
cases  (§  759,  p.  329)  show  also  how  the  organs  may  suffer 
from  an  injury  to  the  spine,  or  interruption  of  the  action  of 
the  great  nerve  which  connects  them  with  the  brain.  What- 
ever may  be  the  cause  of  this  injury,  the  consequence  of  im- 
paired life  and  diminished  power  must  follow,  in  those  parts 
or  organs  which  receive  their  nerves  from  the  spinal  cord 
below  the  point  of  pressure. 


CHAPTER   III. 

If  Nerve  be  injured  or  diseased  in  its  Trunk,  Pain  is  felt  at  its  outer 
Terminations.  —  Injury  of  Optic  Nerve  excites  Sensation  of  Light. — 
Arrangement  of  the  Brain  and  Nerves  like  that  of  Bells  and  Servant 
in  Hotel. 

763.  THE  impression  being  made  on  the  outer  extremity  of 
the  sensory  nerve,  and  the  sensation  being  in  the  brain  at  the 
other  end,  the  nerve  is  a  mere  channel,  or  highway,  through 
which  the  impression  is  carried  inward.     The  healthy  nerve 
receives  no  impressions  and  originates  no  sensations  in  any 
part  of  its  course ;    it  only  carries  those  which  it  receives  at 
its  end ;  and  the  brain  recognizes  and  understands  no  other 
power  or  function  in  the  nerve  than  that  of  receiving  im- 
pressions at  its  outer  extremity.     It  therefore  refers  all  feel- 
ings arid  impressions,  which  come  to  it  through  the  nerve,  to 
those  extremities. 

764.  If,  by  accident  or  disease,  any  impression  is  made 
upon  the  trunk  of  the  nerve,  —  if  we  touch  or  irritate  it,  in  any 
part  of  its  course  between  the  outer  and  inner  ends,  —  this  im- 
pression is  conveyed  to  the  brain ,  but  that  organ  refers  it. 
not  to  the  point  where  the  impression  is  actually  received, 


334  PHYSIOLOGY  AND  HEALTH. 

but  to  the  end  of  the  nerve,  where  impressions  should  be 
received;  and  there,  at  the  extremity,  the  irritation  or  sensa- 
tion seems  to  be.  If  there  is  injury  of  the  nerve,  the  pain  is 
not  felt  at  the  wounded  place,  but  at  the  minute  extremities. 
Thus,  when  we  strike  the  elbow  against  a  table,  and  hurt  the 
trunk  of  the  nerve  that  leads  to  the  fingers,  we  do  not  feel  pain 
at  the  elbow,  which  was  struck,  but  a  tingling  pain  at  the  fin- 
gers, where  the  terminations  of  this  nerve  are  distributed. 

765.  Likewise,  the  pain  of  any  local  disease  of  the  nerve 
is  felt  at  its  extremities.     The  excessively  painful  nervous  af- 
fection of  tic  douloureux  is  felt  on  the  surface  of  the  cheek ; 
but  the  cause  is  not,  as  is  supposed  by  those  unacquainted 
with  the  cause,  in  the  skin  or  flesh,  but  in  the  trunk  of  the 
nerve  leading  from  the  face  to  the  brain.     This  cause  may 
be  situated  any  where  in  the  course  of  the  nerve,  between 
its  outer  ends  in  the  flesh  and  the  inner  end  in  the  brain. 
Wherever  it  may  be,  the  effect  is  the  same,  and  the  painful 
sensations  seem  to  be  at  the  terminations  of  its  branches 
which  go  off  from  the  nerve  below  the  diseased  point. 

766.  The  disease  may  be  in  a  nerve  very  near  the  brain, 
and  yet  the  pain  is  felt  at  its  remote  extremity.     Miss  VV. 
complained  of  very  severe  and  sharp  pains  in  the  arm  and 
hand      It  seemed  to  her,  she  said,  as  if  thousands  of  needles 
were  incessantly  running  through  the  flesh.     For  this,  all 
sorts  of  applications  had  been  made  to  the  seat  of  the  pain, 
and  all  without  effect.     Suspecting  the  pain  had  a  remote 
origin,  her  physician  examined  the  back-bone  at  the  place 
where  the  nerve  went  from  the  spinal  cord  to  the  arm,  and 
there  discovered  great  tenderness  —  pressure  on  this  spot  in- 
creased the  pain  in  the  arm  and  hand.     Blood  was  then  taken 
from  the  back  at  this  point,  and  the  remote  distress  in  the 
arm  and  hand  was  immediately  relieved.     She  afterward  had 
similar  pains,  at  different  times,  in  the  side,  the  stomach,  the 
lower  extremities,  and  the  feet,  and  these  were  relieved  by 
cupping,  or  by  the  application  of  leeches,  or~a  blister,  over 
that  part  of  the  back-bone  where  the  nerve  of  these  several 
suffering  parts  originated. 


BRAIN    AND    NERVOUS    SYSTEM.  335 

767.  The  nerves  of  special  sense  are  subject  to  the  same 
Jaw  as  the  sensory  nerves ;  they  receive  natural  impressions 
at  their  extremities,  but  not  in  their  course.     They  can  con- 
vey to  the  brain,  not  common  feeling  of  pleasure  or  pain,  but 
such  impressions  as  are  made  on  their  outer  terminations, 
which  are  expanded  in  the  several  organs  of  sense.     The 
optic  nerve  conveys  the  impression  of  light,  the  auditory  con- 
veys sound,  the  gustatory  conveys  taste,  and  the  olfactory 
nerve  conveys  the  impression  of  odors.     When  these  nerves 
are  irritated,  or  touched,  or  diseased,  they  still  excite  similar 
sensations.     If  we  close  the  eye  and  press  the  ball  upon  the 
optic  nerve,  an  impression  is  made  upon  the  brain  similar  to 
that  caused  by  light.     If  we  strike  suddenly  upon  the  eye,  or 
even  the  temple,  so  as  to  jar  this  nerve,  the  brain  sees  flashes 
of  light.     Dr.  Howe  has  often  tried  these  experiments  with 
the  blind,  —  both  with  those  who  were  born  in  this  condition, 
and  had  never  seen  light,  and  with  those  who  became  blind 
after  birth,  —  and  they  all  saw  flashes  and  stars. 

768.  When  we  receive  a  blow  on  the  side  of  the  head,  so 
as  to  jar  the  auditory  nerve,  or  when  the  ear  is  diseased,  we 
hear  a  ringing  in  the  ear.     In  some  states  of  disease,  men 
complain  of  bad  taste  on  the  tongue.     In  vain  they  wash  and 
purify  the  mouth  —  still  the  offensive  taste  remains ;  for  it  is 
not  an  impression  made  upon  the  tongue  and  carried  thence 
to  the  brain,  but    the  impression  of  some    disturbance   or 
derangement  of  the  trunk  of  the  nerve  excites  a  disagreeable 
sensation  in  the  brain,  which  refers  it  back,  not  to  the  spot 
which  is  disturbed,  but  to  the  termination  in  the  tongue. 

769.  Whatever  excites  any  nerve  in  its  c<  urse  will  pro- 
duce an  effect  upon  the  brain  similar  to  that  which  is  pro- 
duced  by  impressions  made  upon  its  terrain  itions,  and  the 
sensations  will  be  referred  back  to  the  ends  c  f  the  nerve  as 
their  seats.     An  electric  shock,  if  passed  through  the  nerve 
of  the  ear,  will  give  the  sensation  of  sound ;   and  if  through 
the  nerve  of  the  eye,  the  sensation  of  light.     If  we  apply  a 
piece  of  zinc  and  copper  to  the  upper  and  lower  surface  cf 
the  tongue,  and  let  their  edges  touch  each  other,  they  excite 
a  sense  of  unpleasant  taste. 


336  PHYSIOLOGY    AND    HEALTH. 

770.  This  arrangement  of  the  brain  and  nerves  and  their 
terminations,  or  points  of  impression,  with  their  relation  to 
each  other,  is  similar  to  that  of  the  bells  in  a  hotel  and  the 
servant  who  watches  them.  The  wires  extend  from  the 
several  rooms  to  the  corresponding  bells  in  the  central  room, 
or  the  servants'  hall.  Whenever  the  occupant  of  any  room,  as 
No.  66,  wants  any  thing,  he  pulls  his  wire,  and  the  bell  No. 
66  rings.  The  servant,  seeing  this,  immediately  recognizes 
a  want  in  No.  66,  and  refers  this  to  no  other  room.  His 
only  conception  is  that  of  the  connection  of  bell  No.  66  with 
room  No.  66.  Now,  if  any  one  should  hit  the  wire  between 
these  two  points,  and  ring  the  bell,  the  servant  would  have  the 
same  conception  of  a  want  in  No.  66.  Possibly  this  room 
might  be  cut  off,  and  the  wire  and  bell  remain;  if  then  the 
wire  is  drawn  and  the  bell  rings,  the  conception  is  still  the 
same  of  a  want  in  No.  66.  So  the  brain,  when  it  receives 
any  impression  at  the  inner  end  of  the  nerve  of  the  finger 
or  the  eye,  has  no  other  sensation  than  of  something  pleasant 
or  painful  in  the  finger,  or  of  light  in  the  eye ;  and  even 
though  the  finger  or  the  eye  be  lost,  if  the  nerve  remains  and 
is  irritated,  the  brain  still  has  the  same  sensation. 


CHAPTER   IV. 

Pains  in  amputated  Limb.  —  Motion  excited  by  touching  Motory 
Nerves.  —  Rapidity  of  Nervous  Action.  —  Voluntary  and  Involun- 
tary Organs.  —  Involuntary  Motions  fatigue  less  than  Voluntary. 

771.  THE  last  section  will  explain  some  singular  facts  in 
regard  to  amputated  limbs.  Even  after  the  nerves  are  di- 
vided, or  cut  off,  the  remaining  parts,  if  irritated,  may  excite 
in  the  brain  the  same  sensations  as  if  they  were  entire. 
Sometimes  men,  after  a  leg  has  been  amputated,  complain 
of  suffering  great  pain  in  the  feet  and  the  toes  of  the  sepa- 
rated and  buried  limb  ;  and  some,  believing  there  was  a 
mysterious  connection  between  the  body  and  the  lost  limb, 
have  caused  it  to  be  taken  up  and  examined,  to  see  if  there 


BRAIN    AND    NERVOUS    SYSTEM.  337 

were  any  cause  of  suffering  pressing  upon  it,  while  others 
have  laughed  at  the  fallacious  imagination.  A  gentleman, 
whose  arm  was  recently  amputated  by  a  surgeon  on  account 
of  a  cancer  in  the  hand,  said  that  when  the  end  of  the  nerve 
was  touched  in  the  stump,  he  felt  his  old  pain  in  the  hand. 
In  these  and  similar  cases,  there  was  no  mistake  in  the  sensa- 
tion; the  remaining  trunk  of  the  nerve,  being  pressed  or 
irritated,  carried  this  impression  to  the  brain,  which  referred 
the  pain  to  the  separated  limb,  and  to  no  other.  This  has 
sometimes  happened  many  years  after  amputation.  The 
reasoning  faculty  corrects  the  error,  yet  the  sensation  remains. 

772.  The  same  law  holds  in  regard  to  the  nerves  of  mo- 
tion.    The  muscles  yield  obedience  to  the  mandates  which 
they  receive  from  the  brain.     When  the  mind  wills  to  move 
the  finger,  the  brain  sends  the  volition  and  the  stimulus  of 
contraction  along  the  motory  nerves  to  the  muscles  on  the 
fore-arm,  and  they  contract  and  bend  the  finger.     But  the 
muscles  yield  to  every  stimulus  they  receive  through  the 
motory  nerve.     If,  therefore,  we  prick  or  irritate  one  of  the 
nerves  of  motion,  the  muscles  to  which  it  leads  will  contract; 
if  we  apply  a  galvanic  shock  to  it,  it  will  produce  the  same 
effect ;    and  even  the  limbs  of  the  dead  body,  for  a  short 
time  after  death,  can  be  made  to  move  by  the  powerful  appli- 
cation of  galvanism  to  the  nerve  of  motion. 

773.  False  sensations  are  produced  directly  in  the  brain, 
independent  of  the  nerve,  by  some  disease  which  disturbs, 
or  excites,  or  impresses  the  brain,  at  the  points  where  the 
nerves  terminate.     When  this  impression  is  received  in  the 
brain,  from  the  outer  end  of  the  nerve,  a  true  sensation  is 
excited ;  but  when  it  is  made  directly  upon  the  brain,  by  dis- 
ease or  disturbance,  without  the  intervention  of  the  nerve,  a 
false  sensation  is  the  consequence. 

The  communicating-bells  in  the  hotel  (§  770,  p.  336)  may 
be  rung  by  any  jar,  or  any  thing  moving  them,  independent 
of  the  wires  that  should  pull  them ;  then  the  servant  would 
have  the  usual  idea  of  some  one  ringing  at  the  farther  end 
of  the  wire,  and  something  wanting  in  the  chamber  where 
29 


338  PHYSIOLOGY    AND    HEALTH. 

the  wire  ends.  Whether  the  bell  be  rung  by  some  one  in 
the  chamber,  or  by  some  one  touching  the  wire  in  its  course, 
or  by  any  jar  acting  on  the  bell  itself,  the  same  thought  is 
produced  in  the  mind  of  the  servant  whose  business  it  is  to 
watch  them.  In  like  manner,  whether  the  impression  be  first 
received  at  the  outer  termination  of  the  nerve  in  the  organs 
of  sense,  or  in  the  flesh,  or  on  its  trunk,  or  at  its  inner  ter- 
mination in  the  brain,  the  same  sensation  is  excited  of  sound 
in  the  ear,  sight  in  the  eye,  or  feeling  in  the  flesh. 

774.  These  false  sensations  are  created  in  some  diseases. 
The  insane  sometimes  have  false  hearing  and  vision.     They 
seem  to  hear  tke  sounds  of  voices,  and  even  articulated  lan- 
guage.    When  the  imagination  is  highly  stimulated,  one  sees 
visions.     The  timid  see  frightful  apparitions,  which  seem  to 
assume  as  distinct  a  form  and  color  as  the  real  objects  of  day. 
Sometimes  false  vision  and  false  hearing  exist  together  in  the 
same  person.     He  not  only  sees  the  form  of  the  object,  but 
he  hears  the  sound  of  the  voice.     Men,  when  suffering  from 
delirium  tremens,  are  troubled  with  these  false   sensations. 
They  are  often  frightened  by  the  voices  of  spirits  or  the  sight 
of  enemies.     The  error  in  these  cases  is  not  in  the  eye,  nor 
in  the  ear,  but  in  the  brain  itself.     The  disease  which  disturbs 
this  organ  produces  the  same  sensations  in  it  that  would  be 
produced  if  the  impressions  were  first  made  on  the  eye  or  ear, 
and  then  conveyed  by  the  nerve  to  the  brain. 

775.  Communication  is  very  rapid  through  the  nerves  — 
so  rapid  as  often  to  seem  to  be  instantaneous.     If  we  tread 
upon  a  thorn,  or  a  heated  iron,  the  sensory  nerve  conveys  the 
impression  to  the  brain ;  this  organ  recognizes  the  impression, 
and  then  directs  that  the  muscles  of  the  limb  lift  the  foot  out 
of  danger,  and  sends  this  mandate  through  the  nerve  of  mo- 
tion.    These  two  processes  —  the  passage  of  the  painful  im- 
pression from  the  foot  to  the  brain,  and  of  the  volition  from 
the  brain  to  the  muscle  of  the  foot  —  seem  to  be  simultane- 
ous, yet  they  are  successive. 

776.  Some  of  the  organs  of  the  animal  body  —  the  hands, 
the  legs,  neck,  &,c.  —  are  subject  to  the  exclusive  control  of 


BRAIN    AND    NERVOUS    SYSTEM.  339 

the  will ;  they  only  move  when  directed  by  the  brain.  These 
are  voluntary  organs.  There  are  others,  such  as  the  heart, 
stomach,  &,c.,  which  are  not  under  the  control  of  the  will. 
They  do  not  depend  on  our  attention  or  volition  to  set  them 
in  motion,  and  no  wish  of  ours  can  stay  their  actions.  These 
are  involuntary  organs.  The  organs  of  respiration  are  both 
voluntary  and  involuntary.  They  act  without  our  cognizance, 
and  yet  we  can  accelerate  their  motions,  or  entirely  suspend 
them,  by  efforts  of  the  will.  The  involuntary  are  supplied  with 
nerves,  both  of  sensation  and  of  motion,  as  well  as  the  volun- 
tary organs ;  but  these  nerves  are  not  subject  to  our  command. 

777.  There   are  some   motions  which,  though  they  are 
usually  under  the  exclusive  control  of  the  will,  yet  at  times 
are  involuntary.     We  snatch  the  hand  from  burning  by  an 
effort  of  the  will ;  yet  if  the  fire  be  applied  to  it  when  we  are 
asleep,  and  the  action  of  the  will  is  suspended,  we  snatch  it 
away  with  a  movement  as  involuntary  as  that  by  which  the 
heart  beats  or  the  chest  expands.     The  motions  of  the  hand, 
the  mouth,  and  the  lower  limbs,  are  ordinarily  voluntary,  and 
require  a  distinct  volition  for  their  execution;  yet,  in  certain 
states  of  nervous  disease,  they  become  involuntary.    They  are 
then  beyond  the  control  of  the  will,  and  sometimes  take  place 
even  when  the  will  is  opposed  to  them.    In  cases  of  epilepsy,  in 
the  St.  Vitus's  dance,  and  in  convulsions,  the  muscles  are  con- 
tracted, sometimes  with  great  force,  without  volition,  and  the 
limbs  are  thrown  about,  although  the  sufferer  struggles  to 
resist  it. 

778.  There  are  other  motions  which  are  only  effected  by 
the   direction   of  the  will,  which  yet,  by  practice  and  disci- 
pline, become  apparently,  if  not  really,  involuntary.     Walk- 
ing and  the  playing  upon  a  violin,  an  organ,  or  piano,  require 
the  constant  attention  of  the  mind  of  the  beginner"  to  excite 
and  direct  his  movements.     But  after  practice  he  can  walk 
upon  familiar  paths,  and  play  familiar  tunes,  without  the  ex- 
ertion of  the  will,  and  even  while  his  attention  is  partially 
given  to  other  matters. 

779.  When  motions  become  so  familiar  as  to  be  executed 
without  the  attention  of  the  mind,  they  fatigue  the  body  lesa 


340        _  PHYSIOLOGY    AND    HEALTH. 

than  when  they  require  the  aid  of  mental  action.  Thus, 
when  we  walk,  if  we  lift  the  foot  and  place  it  down  at  each 
step  by  a  special  effort  of  the  mind,  we  shall  be  more  wearied 
than  when  we  walk,  as  we  usually  do,  without  a  special  vo- 
lition for  each  step,  and  have  the  mind  free  to  attend  to  other 
matters.  It  is  easy  to  see  this  difference  of  effect  of  exertion 
in  the  beginner  and  the  practised  performer  of  any  work  or 
art.  The  self-possessed  dancer,  who  moves  with  careless 
ease  through  his  figures,  is  less  exhausted  than  the  timid, 
cautious  dancer,  who  anxiously  watches  every  step.  Both 
of  these  may  move  with  the  same  energy,  yet  the  one  who 
added  mental  action  and  care  to  his  muscular  exercise  drew 
more  upon  the  nervous  energies  than  the  other,  who  exerted 
the  muscles  alone. 

780.  Every  function  of  every  organ  is  dependent  upon 
the  nerves  for  its  power.  The  tongue  has  a  nerve  of  taste, 
one  of  common  sensibility,  and  another  of  motion.  The 
eye  has  one  nerve  of  sight,  another  of  motion.  The  secre* 
tions  of  the  saliva,  of  the  tears,  and  of  the  gastric  juice,  &/c., 
are  dependent  upon  their  peculiar  nerves  to  stimulate  the 
processes.  Each  one  of  these  operations  must  have  its  own 
nerve,  and  that  must  be  in  good  health,  and  connected  with 
the  brain  directly  or  through  the  spinal  cord.  If  this  ner- 
vous connection  is  disturbed  or  suspended,  the  function  is 
impaired  or  fails. 


CHAPTER  V. 

Brain  presides  over  all  Organs  and  Functions.  —  When  it  is  impaired, 
all  Organs  and  Functions  impaired.  —  Not  sensitive.  —  Subject 
to  Laws  of  Body. —  When  pressed,  general  Sensibility  and  Pow- 
er suspended.  —  Subject  to  Growth  and  Decay.  —  Has  large  Sup- 
ply of  Blood.  —  Change  of  its  Particles  increased  by  Exercise. — 
Fatigued  with  Action.  —  Sleep. 

781.  THE  brain  is  the  presiding  genius  over  all  the  pow- 
ers and  Actions  of  life.  It  stands  above  all  and  over  all, 
giving  energy  to,  and  directing  the  motions,  ana  operations 


BRAIN    AND    NEBVOUS    SYSTEM.  341 

of,  all  the  organs  of  the  animal  body.  It  is  of  the  utmost 
importance  in  our  structure,  and,  on  this  account,  very  great 
pains  have  been  taken  to  provide  for  its  well-being,  and  to 
defend  it  from  injury.  The  thick  bones  of  the  skull  are  ar- 
ranged so  as  to  give  the  greatest  strength  to  the  arch,  and  make 
it  capable  of  bearing  very  heavy  weights  without  suffering. 

780.  The  human  brain  fills  all  the  cavity  of  the  skull,  and 
corresponds  with  its  shape.  It  is  the  seat  of  sensation,  of 
thought,  and  volition,  and  the  organ  of  the  mind.  Through 
this  we  recognize  the  impressions  of  external  things.  These 
impressions,  which  are  made  upon  the  organs  of  sense,  and  car- 
ried inward  through  the  nerve,  are  not  perceived  if  the  brain 
is  wanting,  or  if  its  power  of  action  is  suspended.  When  it 
is  unnaturally  oppressed  with  blood,  as  in  apoplexy,  or  with 
water,  as  in  dropsy,  the  light  that  shines  upon  the  eye  is  not 
recognized  by  the  brain,  and  consequently  the  mind  receives 
no  idea  of  external  objects  which  the  light  reflects. 

783.  Although  the  brain  is  the  organ  of  sensation,  it  is 
not  of  itself  sensitive.     It  will  bear  pricking,  or  even  cutting, 
with  less  pain  than  the  fingers.     Many  experiments  tried 
upon  lower  animals  show  that  these  creatures  do  not  mani- 
fest signs  of  pain  when  the  brain  is  cut,  and  even  a  part  taken 
out.     The  same  has  been  observed  in  man  in  cases  of  acci- 
dents.    A  child  fell  from  a  tree  and  fractured  the  skull ;   a 
part  of  the  brain  protruded,  and  the  surgeon  cut  it  off  with- 
out occasioning    apparent  pain.     This  has  frequently  been 
done  with  the  same  result,  and  when  the  mind  was  perfectly 
clear,  and  capable  of  attending  to  the  impressions  communi- 
cated to  it  through  the  brain. 

784.  Whatever  provisions  are  made  by  the  Creator  for  the 
action  and  support  of  the  brain,  are  as  necessary  for  its  well- 
being,  and'  for  the  health  of  the  mind,  as  the  provisions  made 
for  the  heart  and  lungs  are  for  their  well-being,  and  for  circu- 
lation and  respiration.     It  must  have  room  for  action.     The 
cavity  of  the  skull  —  its  resting-place  —  is  just  large  enough 
for  it.     It  needs  so  much  space,  and  no  more,  and  does  not 
safely  bear  any  diminution.     If  this  room  be  diminished  by 

29* 


342  PHYSIOLOGY    AND    HEALTH. 

any  thing  which  crowds  the  brain,  the  organ  suffers.  A  sud- 
den effusion  of  water,  or  pressure  of  bone  from  fracture  of 
the  skull,  or  blood  from  apoplexy,  immediately  suspends  its 
action,  and  then  its  functions,  and  those  of  the  voluntary 
organs  and  the  mind,  are  suspended ;  torpor  and  heaviness 
overwhelm  the  whole  system.  In  other  cases,  where  a  tumor 
grows,  or  water  is  effused  very  slowly,  the  skull  may  expand, 
and  still  leave  room  for  the  brain ;  but  in  most  of  these  in- 
stances, however  slow  their  progress,  the  brain,  sooner  or 
later,  suffers,  from  the  pressure,  and  then  the  physical  and 
mental  powers  are  impaired  or  suspended. 

785.  Sir  Astley  Cooper  relates  a  remarkable  instance  of 
a  man  whose  skull  was  broken  on  a  British  man-of-war,  in 
June,  1799,  in  the  Mediterranean  Sea.     He  was  found  in  a 
state  of  insensibility,  and  incapable  of  voluntary  motion,  arid 
he  remained  in  this  condition  till  May,  1800,  when  he  was 
carried  to  St.  Thomas's  Hospital,  in  London.     There  the  sur- 
geon found  a  piece  of  bone  forced  in,  and  pressing  upon  the 
brain.     When  he  removed  this  bone,  the  man  recovered  his 
sensibility,  and  was  soon  restored  to  health  and  activity,  after 
having -lived  nearly  a  year  in  a  state  of  unconsciousness.* 

786.  The  brain  is  subject  to  the  law  of  growth  and  decay 
of  its  atoms.     It  requires  nourishment  of  new  particles  and 
removal    of  the   old,  as  well    as    all  the  other   organs.     It 
is  therefore  provided    v/ith  an  apparatus  for  nutrition    and 
absorption,    and    arteries   that   bring    the   new    blood,    and 
veins  that  carry  off  the  old  blood  and  the  wasted  particles 
of  matter.     It  seems  to  require  more  blood  for  its  nourish- 
ment, and  for  the  supply  of  its  waste,  than  other  organs  of 
the  same  size,  for  it  receives  a  much  greater  proportion  than 
any  other  part  of  the  body.     The  human  brain  receives  from 
one  fifteenth  to  one  tenth  of  all  the  blood  that  flows  in  the 
body,  and  yet  it  weighs  only  about  one  fortieth  of  the  whole 
frame.     Its  arteries,  being  a  part  of  the  general  circulatory 
system,  beat  in  the  same  manner  and  with  the  same  frequen- 
cy as  the  arteries  of  the  wrist. 

*  Lectures  on  Surgery,  Vol.  I.  p.  233. 


BRAIN    AND    NERVOUS     SYSTEM.  343 

787.  Liicbig  says  that  action  of  the  brain  implies  change  of 
particles  and  waste,  and,  therefore,  a  greater  supply  of  blood. 
To  meet  this  increased  want,  the  arteries  beat  with  greater 
force,   and  send  more  blood,  whenever  the  mind   and  the 
'brain  are  excited  or  active.     Sir  Astley  Cooper  saw  this  in 
a  young  man  who  had  lost  a  portion  of  the  skull.     "  His 
brain  could  be  distinctly  seen  beating,  through  the  opening 
of  the  skull ;  "   and,  whenever  he  was  irritated  by  any  oppo- 
sition, the  pulsation  was  much  more  violent,  and  it  became 
more  quiet    when  he  was  calm,  and   his  mind  was   easy.* 
There  was  a  girl  in  Montpellier,  France,  who  had  lost  a  large 
portion  of  the  scalp  and  skull.     Her  brain  could  be  seen  for 
a  considerable  extent  of  surface.     "When   she  was    in    a 
dreamless  sleep,  her  brain  was  motionless,  and  low  within 
the  cranium;  but  when  her  sleep  was  imperfect,  and  .she  was 
agitated   with   dreams,    her   brain  moved"   and  beat,   more 
blood  was  sent  to  it,  the  arteries  expanded,  and  the  brain 
protruded  through  the  hole  in  the  bone.     This  protrusion 
was  greater  in  active  than  in  calm  dreams ;  and  when  she 
was  awake,  the  same  difference  was  observed,  consequent 
upon  the  activity  and  the  quiescence  of  her  mind.     If  she 
was  in  vigorous  thought,  the  brain  swelled,  and  protrusion 
was  very  observable.t 

788.  The    eye  becomes   weary    with    long   exposure   to 
light,  and  seeks  rest  and  relief  in  shade ;  and,  if  not  thus 
relieved,  it-  finds  it  difficult  to  discriminate  objects.     The 
muscles,  also,  are  fatigued  with  long  and  continuous  exer- 
tion, and  are  incapable  of  contraction.     Rest  restores  this 
power.    So  the  brain  is  fatigued  with  long  and  uninterrupted 
attention  to  subjects  of  deep  thought,  and  incapable  of  fix- 
ing its  attention  upon  matters  of  a  grave  nature ;  then  it 
wants,  and  must  have,  opportunity  of  rest  to  recover  its 
energies ;   and,  if  this  is  not  granted,  the  brain  and  the 
mind  will  be  weakened  or  disordered. 

789.  Sleep  is  the^natural  rest  of  the  brain.     It  gives  rest 
to  the  mind  and  to  the  voluntary  organs  of  the  body.    The 

*  Surgical  Lectures. 

f  Combe,  255.    Annals  of  Phrenology,  No.  I.  p.  39. 


344  PHYSIOLOGY   AND   HEALTH. 

brain,  and  the  nerves  of  sensation,  and  those  that  convey 
volition,  sleep ;  but  the  motory  nerves  of  the  heart  and  arte- 
ries, and  the  lungs,  never  sleep.  When  a  man  dreams,  his 
brain  is  not  in  complete  rest;  and,  in  the  cases  of  sleep- 
walking, the  sleep  of  the  brain  and  of  the  nervous  system  is 
still  less  perfect,  and  of  course  the  system  is  less  refreshed 
by  it.  That  sleep  is  most  refreshing,  and  the  best  recruits 
the  frame,  in  which  there  is  neither  dream  nor  motion,  but 
absolute  inaction  of  all  the  voluntary  powers. 


CHAPTER    VI. 

Night  is  the  proper  Season  for  Rest  of  the  Brain.  —  Brain  gains 
Power,  by  Exercise.  —  Weakened  by  Over-Action.  —  Connected 
with  other  Organs;  with  Lungs,  Stomach,  Muscles.  —  Effect  of 
Alcohol  on  Brain  and  Muscle^  ;  on  Mechanical  Skill ;  on  Use  of 
Tools. 

790.  There  is  a  natural  connection  of  the  action  and  in- 
action of  the  brain  with  the  alternation  of  day  and  night. 
The  brain,  as  well  as  the  muscles,  has  more  vigor  and  a 
greater  power  of  action  in  the  light  of  day,  and  is  more  prone 
to  rest  and  to  recruit  itself  in  the  darkness  of  night.     The 
day  is,  then,  the  appropriate  time  for  mental,  as  well  as  bodily 
labor,  and  the  night  the  proper  season  for  sleep  of  the  mind 
and  the  brain. 

791.  The  stillness  of  the  night,  when  the  busy  world  is 
quieted,  and  we  are  secure  from  interruption,  seems  to  in- 
vite the  student  to  his  books.     Then  the  mind  is  not  dis- 
turbed  with  other  claims   upon  its  attention,  and  there  is 
then  better  opportunity  for  concentration  of  thought  upon 
any  subject.      Therefore  some   attend  to  external   matters 
during  the  day,  or  even  sleep  during  some  portion  of  it,  and 
reserve  their  mental  labor  —  the  toil  of  the  brain  —  for  the 
night.     It  is  an  unprofitable  habit  of  some  clergymen  to  write 
their  sermons  in  the  evening  or  night  before  they  must  be 
delivered,  and  then,  by  concentrating  the  whole  energy  of 


BRAIN    AND    NERVOUS    SYSTEM.  345 

the  brain  upon  their  proposed  labor,  accomplish  their  work. 
This  is  frequently  done,  and  with  temporary  success ;  but  it 
is  at  the  cost  of  the  permanent  power  of  the  brain,  as  well  as 
of  the  general  health  of  the  body.  Naturally,  the  brain  has 
the  greatest  power  of  labor,  and  the  mind  the  greatest  energy 
of  thought,  in  the  early  part  of  the  day,  and  less  in  the  latter 
part,  and  least  in  the  night;  and  consequently  all  mental 
labor  exhausts  the  brain  more  in  the  evening  and  night  than 
in  the  morning  and  the  bright  hours  of  day. 

792.  The  brain  gains  strength  by  moderate  and  appropriate 
exercise,  when  this  is  interchanged  with  rest;   and,  if  fre- 
quently called  upon  to  exert  itself,  it  acts  with  greater  en- 
ergy, just  as  the  muscles  become  strong  with  use,  or  the  skin 
hardy  with  exposure.    It  is  easy  to  see  the  difference  of  men- 
tal power  in  the  laborer,  —  who  uses  his  muscles,  and  not 
his  brain,  and  works  only  under  the  direction  of  another, — 
and  in  the  employer,  whose  brain  is  ever  active  with  his 
plans  of  business.     But  excessive  mental  toil  exhausts  the 
power  of  the  brain.    Long-protracted  labor  of  the  brain,  with 
insufficient  or  no  intervals  of  rest,  waste  and  weaken  it ;  and 
any  over-exertion,  for  even  short  periods,  is  injurious.     The 
brain  can  bear  excess  of  action  no  better  than  the  muscles. 
The  blacksmith  or  the  stone-cutter  can  as  safely  do  two  days' 
work  every  Saturday  afternoon  and  night,  as  the  clergyman 
can  write  his  sermons  in  the  same  time. 

793.  Although  the  brain  is  placed  above  and  over  all  the 
other  organs  of  the  body,  to  give  them  life,  and  energy,  and 
direction,  yet  it  is  dependent  upon  them  for  its  own  health 
and  power.     It  has   intimate    connections    and    sympathies 
with  each  one  of  the  others ;  it  is  strong  with  their  strength, 
and  weak  with  their  weakness ;  it  enjoys  their  pleasures,  and 
suffers  with  their  pains. 

794.  The  brain   is   constantly  connected  with,  and  imme- 
diately dependent  on,  the  heart.     It  must  have  a  large  and  un- 
failing supply    of  blood    at   any    time.      If  the  heart  is  dis- 
eased, and  cannot  admit  the  return  of  the  venous  blood,  the 
brain  is  crowded  with  it ;  then  pain  and  confusion,  and  even 


346  PHYSIOLOGY    AND    HEALTH. 

insensibility,  may  follow.  It  needs  and  receives  more  blood 
during  its  action  and  excitement,  and  less  in  its  quiescence 
and  calmness.  The  heart  must  therefore  be  in  good  health, 
and  able  to  supply  the  greater  want  of  the  active  and  excited 
brain.  But,  when  the  heart  is  diseased,  it  cannot  send  this 
increase  of  blood ;  and,  if  it  attempts  it,  it  struggles  in  vain, 
and  great  distress,  and  even  death,  may  follow.  Persons  who 
suffer  from  disease  of  the  heart,  cannot  safely  bear  any 
mental  excitement.  For  this  reason,  a  celebrated  surgeon, 
who  had  this  disease,  continually  guarded  himself  against 
any  irritation  of  temper  or  agitation  of  mind,  yet  was  sud- 
denly excited  on  an  occasion,  arid  immediately  died. 

795.  The  connection  of  the  brain  with   the   lungs   is   not 
less    apparent   than  witli  the  heart.     The    brain    needs    not 
merely  a  large  quantity  of  blood,  but  that  of  the  purest  and 
the  best  quality.     Whenever  the  blood  is  imperfectly  purified 
of  its  carbon,  either  from  defect  of  the  respiratory  appara- 
tus or  from  want  of  pure  air,  the  brain  feels  it  immediately. 
If  the  waste  and  dead  particles  are  not  carried  off  from  the 
blood  in  the  lungs,  the  impure  blood  is  sent  again  through 
the  heart  and  arteries  to  supply  the  body ;  the  brain  surfers 
more  than  the  other  organs,  and  becomes  inactive,  and  often 
painful,  and  the  mind  dull.     The  audience  of  a  close  and 
crowded    lecture-room,    and     children    in    an    unventilated 
school-room,  lose  their   mental  energy  and  their  power  of 
application.     (§§  383,  384,  p.  165.) 

796.  The  sympathies  between  the  brain  and  stomach  are 
familiar  to  us.     Most  men  have  been   compelled  to  know 
how  these  two  organs  suffer  together  in  sick  headache.     The 
frequent  pains  in  the  head  are  generally  to  be  referred  to  the 
derangement  of  the  stomach,  and,  when  this  organ  is  relieved, 
the  brain  is  usually   well.     Dyspeptics   complain  of  much 
headache,  and,  on  the  contrary,  those  who  suffer  from  disease 
of  the  brain  are  often  troubled  with  digestive  disturbance.     A 
blow  on  the  head  will  often  occasion  vomiting,  and  excess 
of  action  of  the  brain  will  sometimes  suspend  the  action  of 
the  organs  of  digestion. 


BRAIN     AND    NERVOUS    SYSTEM.  347 

797.  The  brain  controls  the  actions  of  all  the  muscles, 
and  supplies  them  with  the  stimulus  of  motion  through  the 
nerves  which  connect  them  together.     The  muscles  are  thus 
completely  dependent  on  the  brain  for  their  vitality  arid  their 
energy.     They  can  have  no  more  life  and  energy  than  that 
controlling  organ  has  to  give  them.     If  it  is  impaired,  the 
power  of  muscular    contraction  is  diminished.     When   the 
brain  is  pressed  and  incapable  of  action,  the  muscles  are 
palsied  and  the  limbs  motionless.     An  injury  of  the  head, 
which  destroys  sensibility, paralyzes  the  frame;  and  then  the 
sufferer  can  neither  stand  nor  move,  for  all  voluntary  action 
is  suspended.     It  is  the  brain  that  directs  every  contraction 
of  the  muscles,  and,  by  its  complete  discipline,  harmonizes 
their  actions  so  that  the   desired  motions  are    produced  in 
the  limbs;  and  thus  the  movements  of  the  musical  performer, 
the  skilful  mechanic,  and  of  the  writer,  are  executed  with 
beautiful  precision.  (§§  636—640,  p.  276.)     But  if  any  thing 
disturbs  the  brain,  and  suspends  or  impairs  its  balance  of 
action,  it  loses  this  control  over  the  muscular  actions,  and 
they  become  irregular. 

798.  Alcohol,  in  any  of  its  forms,  excites  the  brain  and 
nervous  system,  and  disturbs   their  actions,  and  impairs  or 
suspends  their  control  over  the  muscles.     For  this  reason, 
the  drunken  man  reels  or  staggers ;  he  is  unable  to  direct 
his  feet  and  put  them  in  the  appointed  places.     Some  of  the 
muscles  may  contract  too  much,  and  others  too  little,  and 
carry  his  feet  too  far,  or  not  far  enough,  to  one  or  the  other 
side ;  or  they  may  not  contract  even  sufficiently  to  hold  him 
up,  and  then  he  falls  to  the  ground.     When  he  attempts  to 
work  with  his  hands,  he  finds  the  same  difficulty,  the  same 
want  of  control  over  the  muscles  that  move  the  arms,  hands, 
and  fingers.     He  cannot  direct  them  and  the  tools  which  he 
holds  with  the  desired  precision,  and  therefore  often  fails  of 
striking  the  proper  point.     He  may  strike  where  he  least 
intended,  and  do  injury  to  his  work  or  to  his  own  person. 
The  muscles  of  his  tongue,  also,  suffer  in  the  same  way,  ind 
he  articulates  indistinctly. 


348  PHYSIOLOGY    AND    HEALTH. 

799.  After  the  brain  and  nervous  system  have  been  fre- 
quently excited,  and  their  control  of  the  muscular  actions 
interrupted  with  stimulating  spirits,  they  do  not  recover  the 
complete  command  of  the  muscles  when  the  fits  of  intoxica- 
tion pass  away.     Therefore  old  drunkards,  even  when  sober, 
walk  with  a  faltering  step  and  work  with  an  unsteady  hand 
They  lose  their  power  of  skilful  workmanship.     If  they  are 
nice  mechanics,  they  impair  their  skill  by  their  intemperance, 
and  are  then  compelled  to  apply  their  hands  to  coarser  work ; 
and  some  are  obliged  to  give  up  their  handicraft  altogether, 
and  betake  themselves  to  the  rudest  of  common  labor. 

800.  There  was  a  very  skilful  worker  in  iron.     He  was 
remarkable  for  the  dexterous  use  of  his  hands,  and  the  beauty 
and  fitness  of  his  manufactured  articles.     But  he  became  in- 
temperate, and,  after  some  years,  lost  the  exact  command  of 
his  hands,  and  the  power  of  exact  adaptation  of  his  tools  to  the 
material  on  which  he  worked.     He  gave  up  his  nice  work, 
and  manufactured  coarser  articles.     In  process  of  time,  his 
muscles  became  less  and  less  under  his  control,  and  he  gave 
up  his  shop  and  trade  altogether ;  and,  for  the  rest  of  his  life, 
he  sawed  wood,  dug    in    the  ground,  carried   the   hod   for 
masons,  doing  nothing  b'ut  the  roughest  work,  which  required 
the  least  discipline  of  the  brain  and  command  of  the  muscles. 

801  In  this  undisciplined  condition  of  the  brain,  and  ab- 
sence of  command  of  the  muscles,  the  intemperate  man 
loses  the  power  of  self-protection,  and  consequently  meets 
with  more  accidents  than  other  men.  When  he  walks,  he 
makes  missteps,  he  loses  his  balance,  and  stumbles  over  small 
obstacles.  If  he  drives  a  nail,  he  is  not  sure  to  direct  the 
hammer  so  as  to  strike  the  head;  he  may  often  hit  his  fin 
gers.  If  he  uses  sharp  tools,  he  may  strike  in  a  wrong 
direction,  or  his  instrument  may  slip  and  cut  his  own  flesh. 
A  mechanic,  when  he  wounded  his  knee  with  an  axe,  com- 
plained of  his  very  frequent  ill  luck.  He  said  he  was  al- 
ways meeting  with  accidents.  But  a  short  time  before,  he 
bruised  his  finger  with  a  hammer  while  driving  a  nail ;  then 
he  cut  his  foot ;  now  he  had  cut  his  knee.  He  was  intern- 


BRAIN    AND    NERVOUS    SYSTEM.  349 

perate ;  and,  though  not  always  intoxicated,  —  probably  not 
so  even  at  the  time  of  his  injuries,  —  yet  he  had  lost  the  per- 
fect control  of  his  muscular  actions,  and  could  not  direct  his 
blows  safely 

CHAPTER   VII. 

Brain  Seat  of  Mind,  Affections,  Passions.  —  Power  and  Action  of 
Mind  limited  by  Power  of  Brain.  —  Stimulation  of  Brain  stimulates 
Mind,  and,  on  the  contrary,  Mind  subject  to  Liabilities  of  Brain. — 
Impaired  by  Indigestion;  by  Excess  of  Eating;  by  Hunger. — 
Moral  Feelings  affected  by  Stomach.  —  Effect  of  Cheerfulness. 

802.  The  brain  is  the  only  avenue  which  the  mind  has  to 
the  outward  world.     It  is  the  organ  through  which  the  intel- 
lect acts  in  regard^io  other  minds  and  to  external  things.     It 
is  the  seat  of  the  passions,  of  the  affections,  and  of  the  moral 
feelings.     The  immortal  mind  —  the  spirit  itself —  is,  indeed, 
something  more  than,  and  different  from,  the  physical  brain ; 
yet  the  Creator  has  so  connected  these  together  in  this  life, 
that  we  know  of.  the  operations  of  one  only  through  the  me- 
dium of  the  other.     As  the  eye  is  the  organ  of  sight,  and  the 
ear  the  organ  of  hearing,  so  the  brain  is  the  organ  of  percep- 
tion, of  thought,  and  affection.     The  eye  is  not  sight,  though 
there. is  no  sight  without  it.     The  ear  is  not  hearing,  though 
there  is  none  independent  cf  it.     So  the  brain  is  not  mind, 
though  there  is  no  mental  operation  without  it. 

803.  The  brain    being   the  only  instrument  with  which 
the  mind  plays^  here,   they    are   indissolubly  connected  to- 
gether in  this  life.     Their  powers  of  action  have  equal  limits. 
Whatever  we  may  say  about  the  illimitable  power  of  the  ex- 
pansive  mind,  it  can  move  no  farther  nor  faster  than  the 
brain  can  go.     Whenever  the  brain  is  weary,  the  mind  is 
weary.     Whenever  the  brain  wants  rest  and  sleep,  the  mind 
needs  the  same.     The  brain  can  make  only  a  definite  amount 
of  exertion,  and  work  only  a  definite  number  of  hours,  and 
then  it  must  suspend  all  labor,  and  lie  down  to  rest  in  com- 
plete inaction.     The  mind   can  do  no  more.     Precisely  at 

30 


350  PHYSIOLOGY   AND    HEALTH. 

the  point  where  the  brain  is  fatigued,  the  intellect  is  fatigued, 
and  when  the  brain  sleeps,  the  mind  falls  into  a  state  of  un- 
consciousness. 

804.  Whatever  excites  the   brain  excites  the  mind.     The 
wine  that  first  stimulates  and    then   oppresses  the  nervous 
system,  also  at  first  quickens  mental  action,  and  then  over- 
whelms the  mind  with  stupor.     Whatever  stimulating  sub- 
stance sends  more  blood  to  the  brain,  excites  the  mind  to 
quicker  action,  and  gives  it  a  greater  grasp  of  thought.     On 
the  contrary,  whatever  excites  the  mind  to  unusual  action,  oc- 
casions unusual  flow  of  blood  to  the  brain.     The  arteries  of 
the  brain  were  seen  to  beat  (§  787,  p.  343)  when  the  passions 
were  irritated  or  the  mind  excited,  and  even  when  the  sleeper 
was  troubled  with  dreams.     The  blood  flows  in  unnatural 
abundance  through  the  brain  of  a  man  in  passion,   and  of 
the  scholar  while  he  is  studying  with  all  his  mental  activity. 
The  reverse  happens  when  any  emotion  oppresses  the  mental 
energies.     When  one    is    appalled  with  fear,  or   depressed 
with  sorrow,  his   countenance  is  pale  with  the  absence  of 
blood,    and    the    brain    is   supplied  in  the  same   imperfect 
degree. 

805.  The  mind  is  subject  to  all  the  liabilities  of  the  brain. 
It  shares  in  all  its  sympathies  with  other  organs  of  the  body. 
When  the  brain  is  pressed  with  blood,  as  in  apoplexy,  or  with 
a  piece  of  broken  skull,  the  mind  is  stupid.     When  the  head 
:aches  from  breathing  foul  air,  the  mind  is  dull :  and  it  is 
torpid   when    one   breathes    charcoal    gas.      When    alcohol 
gently  increases  the  flow  of  blood  in  the  head,  the  mind  is 
more  active,  and  the  spirits  more  lively ;  and  when  this  flow 
is  a  little  more  increased,  and  the  brain  stimulated  too  highly, 
the  mind  loses  its  balance,  the  thoughts  run,  and  the  tongue 
talks  wildly ;   and  a  still  further  increase  of  blood  stupefies 
the   brain,   and    then    the  mind   is  torpid,  and  insensibility 
follows. 

806.  I  lately  saw  a  child  whose  brain  seemed  to  be  torpid, 
but  whose  whole  body  was  writhing  in  convulsions.     The 
brain  was  oppressed,  and  the  child  was  senseless;  she  could 


BRAIN    AND    NERVOUS    SYSTEM.  351 

neither  hear,  nor  see,  nor  understand  ;  but  the  motory  nerves 
were  excited,  and  the  muscles  thrown  into  violent  action. 
The  child  had  eaten  great  quantities  of  unripe  fruit,  which 
the  stomach  could  not  digest.  But  as  soon  as  the  stomach 
was  relieved  of  this  unnatural  load,  the  convulsions  ceased, 
and  the  consciousness  returned.  But  she  had  no  recollec- 
tion of  what  had  passed.  Here  was  decided  proof  that  the 
brain  and  nerves  were  connected  with  the  digestive  organs. 

807.  Indigestion  and  nausea,  which  create  pain  in  the 
head,  impede  mental  action.  When  suffering  from  dyspep- 
sia, the  student  cannot  apply  his  thoughts  to  weighty  subjects, 
and  the  accountant  is  unwilling  to  attend  to  his  figures,  and 
make  his  calculations.  Recently,  a  merchant,  whose  dinner 
oppressed  him,  found  his  mind  so  confused  that  he  left  his 
counting-room  and  went  home  to  recruit  his  powers.  Hav- 
ing a  taste  for  grave  matters,  he  attempted  to  read  history ; 
but  he  could  not  confine  his  attention  to  the  subject.  He 
then  tried  to  read  an  exceedingly  interesting  biography  —  the 
life  of  a  friend;  but  even  this  required  too  much  mental  ex- 
ertion ;  and  at  last  he  betook  himself  to  one  of  the  lightest 
of  t  les,  —  Valentine  Vox,  —  which  he  said  required  all  the 
energy  of  mind  that  he  could  then  exert. 

8C8.  The  same  indisposition  to  mental  exertion  follows 
after  eating  an  excessive  meal.  Great  eaters,  who  keep  their 
digestive  organs  constantly  at  work,  have  usually  but  little 
intellectual  activity.  They  prefer  sleeping  to  thinking,  arid 
study  is  a  burden  to  them.  On  the  contrary,  hunger  is  none 
the  less  an  enemy  to  mental  labor,  (§  154,  p.  73,)  and  in 
cases  of  extreme  hunger,  the  mind  cannot  apply  its  powers 
to  any  matter  of  thought  or  business ;  and  in  starvation  it 
loses  its  self-control  entirely,  and  insanity  sometimes  follows. 

809.  The  moral  powers  and  affections  are  influenced  by 
the  state  of  the  digestive  organs.  A  sour  stomach  produces 
a  sour  temper,  and  men  are  usually  thought  to  be  cheerful 
and  good-natured  while  at  dinner.  Dyspeptics  are  frequently 
irritable  and  suspicious.  They  are  sometimes  gloomy,  and 
look  upon  all  about  them  with  fear  and  distrust.  A  friend, 


352  PHYSIOLOGY    AND    HEALTH. 

who  is  naturally  of  a  kind  and  generous  temper,  but  subject  to 
occasional  fits  of  painful  indigestion,  said,  a  few  weeks  since, 
that  the  world,  at  different  times,  wore  two  entirely  different 
aspects,  varying  according  to  the  state  of  his  stomach. 
"  Now  all  is  bright  and  promising  ;  I  have  an  abundance  of 
friends,  and  every  body  is  kind  ;  I  see  nothing  to  mar  the 
present,  and  feel  no  doubt  of  the  future.  But  last  week,  when 
my  stomach  was  in  trouble,  and  my  food  oppressed  me,  every 
thing  was  as  different  as  darkness  from  light.  Then  it 
seemed  that  I  had  no  friends,  and  no  one  cared  for  me ;  the 
world  was  selfish,  and  gave  me  no  sympathy  nor  encourage- 
ment; their  actions  and  their  speech  were  hostile  to  my 
character  and  peace.  I  put  an  unfavorable  construction  upon 
what  was  said  to  and  concerning  me.  The  very  language 
that  now  seems  to  be  that  of  kindness,  seemed  then  to  be  in- 
jurious. The  present  was  then  full  of  doubt  and  fear,  and 
the  future  promised  nothing  better.  The  cloud  has  now 
passed  away,  the  sun  shines  brightly  again  in  my  heart  and 
my  prospects.  It  is  allowing  to  the  state  of  my  stomach." 

This  is  not  an  uncommon  case.  It  may  be  frequently 
found,  though  perhaps  in  a  less  degree,  and  sometimes  in  a 
greater  degree  in  the  world.  The  connection  between  the 
indigestion  and  depression  of  spirit  or  suspicious  temper 
is  not  so  clear  ;  but  it  is  none  the  less  certain. 

810.  On  the  contrary,  the  states  of  the  mind  and  feelings 
affect  the  stomach  and  the  other  physical  organs  and  their  func- 
tions.  Cheerfulness  excites  the  respiration,  and  favors  the 
purification  of  the  blood.  (§  322,  p.  143.)  It  aids  the  action 
of  the  heart  (§  235,  p.  108)  and  the  nutritive  process  through- 
out the  body.  But  in  sorrow  and  care,  the  respiration  is 
languid,  the  purification  of  the  blood  imperfect,  the  heart 
moves  heavily,  and  nutrition  is  sparing.  Muscular  power  is 
increased  and  diminished  by  the  same  causes.  The  languid 
limb  goes  with  the  heavy  heart,  and  the  laborer  works  feebly 
whose  spirit  is  weighed  down  with  sorrow  or  discontent. 
(§  713,  p.  308.)  Those  who  gain  add  more  and  more  energy 
to  their  exertions,  and  those  who  labor  unsuccessfully  make 


BRAIN    AND    NERVOUS     SYSTEM.  353 

fainter  and  fainter  efforts.  These  principles  have  been  known 
from  the  times  of  old,  when  Solomon  said,  "  A  merry  heart 
doeth  good  like  rneHicine,  but  a  broken  spirit  drieth  the 
bones." 

809.  The  work  of  digestion  goes  on  best  in  company  with 
the  warm  and  gentle  affections,  where  love  is  predominant, 
and  tenderness  animates  the  soul.  (§  166,  p.  78.)  There 
the  food  is  best  converted  into  blood,  and  the  blood  into 
flesh,  and  this  has  most  permanent  power  of  action.  But 
bitter  and  harsh  feelings  impair  this  work  in  all  its  processes. 
Fat  people  are  usually  supposed  to  be  cheerful  and  contented 
with  themselves  and  the  world.  They  are  not  easily  dis- 
turbed by  the  ordinary  affairs  about  them.  But  the  lean  are 
usually  more  anxious  and  careful ;  they  worry  and  fear  more; 
they  are  not  so  easily  satisfied,  and  are  more  affected  by  the 
mischances  of  every-day  life. 

812.  Thus  there  is  a  remarkable  and  a  beautiful  harmony 
between  the  flesh  and  the  spirit.  Cheerfulness  and  love  add 
to  the  physical  powers ;  and,  on  the  contrary,  robust  health 
and  bodily  vigor  aid  in  the  buoyant  flow  of  spirits.  Melan- 
choly people  are,  therefore,  usually  less  healthy  and  strong,  as 
well  as  less  happy,  than  the  cheerful ;  and,  moreover,  they  are 
more  unprofitable  workers. 


CHAPTER  VIII. 

Brain  superintends  physical  and  mental  Operations ;  sustains  these 
well  when  it  is  vigorous,  and  several  at  the  same  Time,  if  they 
are  easy,  but  not  if  they  become  difficult.  —  Mind  works  best 
when  Body  is  easy.  —  Uncomfortable  Seats  interrupt  Study. — 
Bad  Light  and  Temperature,  and  Fatigue,  have  the  same  Effect. 

813.    THE  brain  superintends,  or  is  connected  with,  the 
operations  of  all  the  organs  of  the  body ;   both  those  which 
are  involuntary  and  beyond  the  control  of  the  will,  and  those 
30* 


354  PHYSIOLOGY    AND    HEALTH. 

which  we  direct  by  our  volition.  The  movements  of  the 
limbs  by  the  contraction  of  the  muscles,  the  circulation  of 
the  blood,  digestion,  nutrition,  respiration,  the  development 
of  heat,  the  secretion  of  all  the  fluids,  depend  upon  the  brain. 
The  mentaj  and  moral  actions,  the  reception  of  knowledge 
through  the  organs  of  sense,  thought,  volition,  the  feelings, 
and  the  passions,  are  also  connected  with  the  brain.  Every 
living  action  depends  on  the  life  of  this  organ,  and  every 
correct  action  depends  upon  its  soundness.  This  organ  and 
its  powers  are  placed*  partially  under  our  control ;  we  think, 
we  feel,  we  indulge  in  passion  through  it,  and  we  direct  its 
energies  to  muscular  action.  But  it  gives  its  energies  to  the 
involuntary  actions  without  our  will.  We  are  responsible  for 
the  u^e  of  its  power  in  all  voluntary  actions,  and  we  may  so 
use  it  as  to  interfere  with  its  control  of  the  involuntary 
actions. 

814.  The  brain  performs  all  these  offices  well  when  it  is 
fresh  and  vigorous ;  but,  whenever  the  nervous  energies  are 
exhausted  or  reduced,  the  brain  works  languidly,  and  all  the 
functions  of  the  other  organs  also  languish.     When  we  are 
fatigued  with  muscular  effort,  digestion  is  feeble.  (§  162,  p. 
77.)     When  the  powers  of  the  nervous  system  are  diminished 
by  excessive  mental  labor,  the  animal  heat  is  sparingly  gen- 
erated, (§  434,  p.  186;)   or  in  whatever  way  the  sustaining 
power  of  the  brain  is  reduced,  it  is  less  able  to  support  any 
of  the  bodily  or  mental  operations,  until  it  shall  renew  its 
power  by  sufficient  rest. 

815.  The  brain   sustains  and   superintends  some  of  the 
voluntary,  and  all  the  involuntary,  operations  at  the  same  time. 
We  can  walk,  and  breathe,  and  think,  at  the  same  moment, 
when  neither  of  these  requires  any  great  effort  or  attention  of 
the  mind.     But  the  brain  cannot  concentrate  its  power,  so  as 
to  make  any  unusual  exertion,  upon  more  than  one  thing  at 
a  time.     If,  therefore,  any  one  of  these  operations  becomes 
difficult,  or  if  we  perform  it  with  unusual  energy,  and  conse- 
quently demand  of  the  brain  extraordinary  power  of  direction 
or  exertion,  it  can  give  but  sparing  energy  and  power  to  the 


BRAIN    AND    NERVOUS    SYSTEM.  355 

performance  of  the  other  operations,  (§  70S,  p.  307,)  or  per- 
haps it  must  suspend  them  altogether. 

816.  If  any  of  the  involuntary  operations,  which  require 
the  direction  of  the  brain,  but  not  the  consciousness  of  the 
mind,  becomes  difficult,  and  requires  mental  effort,  the  brain 
can  do  little  more  than  attend  to  it.     Thus  we  maintain  res- 
piration and   carry  on  the  other  operations  in  conjunction 
with  it ;   but  in  paroxysms  of  asthma,  or  in  croup,  when  the 
whole  nervous  power  is  concentrated  in  the  effort  to  breathe, 
all  labor  of  body,  and  all  thought    must  be  suspended,  and 
the  whole  nervous  energy  devoted  to  respiration. 

817.  An  accomplished  musician  can  play  several  parts  of 
a  tune  with  his  fingers  upon  the  organ,  and  read  and  sing  the 
words  of  the  song,  or  call  the  figures  of  the  cotillon ;  but  if 
the  tune  is  riot  familiar,  —  if  it  requires  a  special  effort  of  the 
attention  to  read  the  notes,  —  he  can  neither  sing  the  words  of 

,the  song  nor  call  the  figures  of  the  dance. 

818.  If  the  brain  is  occupied  by  any  other  efforts,  or  by 
any  disagreeable  sensations,  it  cannot  give  its  full  attention 
to  any  mental  operation.     When  a  man  wishes  to  give  the 
undivided  energy  of  his  mind  to  any  subject,  he  places  him- 
self in  such  a  position  that  his  whole  frame  is  most  easy.     If 
he  sits,  he  selects  a  chair  suited  to  the  form  of  his  frame,  so 
that  his  body  and   limbs  are  supported  without  effort ;    and 
regulates  the  temperature  of  the  room,  so  that  he  is  neither 
hot  nor  cold;   and  the  light,  so  that   it.  Is  neither  painfully 
glaring   nor   insufficient   for   the   easiest   perception.     Some 
prefer  a  standing  posture,  and  others  will  walk  their  rooms: 
but  most  prefer  the  sitting  position  while  they  are  in  intense 
thought ;   but,  in  either   arrangement,  nothing  external  calls 
the  brain  from  the  subjects  of  study. 

819.  It  is  the  fault  of  many  school-rooms,  that  they  are  so 
constructed  that  a  very  considerable  portion  of  the  attention 
of  the  pupils  is  taken  up  with  their  uncomfortable  physical 
sensations,  and  with  their  endeavors  to  obtain  relief.     Instead 
of  the  comparatively  easy  chairs,  somewhat  adapted  to  their 
forms,  which  children  are  accustomed  to  enjoy  at  home,  these 


356  PHYSIOLOGY    AND    HEALTH. 

school-rooms  are  usually  furnished  with  seats  of  one  kind, 
and  nearly  of  one  size,  and  made  without  regard  to  the  hu- 
man shape.  These  seats  are  sometimes  without  backs,  and 
sometimes  with  backs  so  square  and  perpendicular  as  to  give 
no  comfortable  support.  They  are  often  so  high  that  the 
smaller  boys  find  no  rest  for  the  foot,  or  so  low  that  the 
larger  boys  have  not  the  usual  support  for  the  thigh.  They 
are  often  built  on  an  inclined  plane,  upon  which  the  foot 
tends  to  slide  forward  and  downward,  and  the  child  is  then 
continually  reminded  of  his  position  by  his  uncomfortable 
feelings,  and  is  compelled  to  make  constant  exertion  "of  his 
muscles  to  prevent  his  feet  sliding  forward. 

820.  Some  school-houses  are  so  situated   as  to  be  pro- 
tected neither  from  the  severest  storms  of  winter  nor  from  the 
burning  sun  of  summer.     They  are  often  imperfectly  warmed, 
and  the  temperature  is  unequal  in  the  various  parts.     There 
are  many  whose  chilly  feet,  in  the  cold  season,  make  irresisti- 
ble drafts^upon  their  attention;  and,  in  the  warm  season,  in 
the  absence  of  both  shade-trees  and  blinds,  or  curtains,  the 
heat  and  the  glare  of  the  sun  make  equal  claims  upon  their 
feelings,  and  withdraw  their  attention  from  their  books.     It 
is  all  in  vain  that  their  teachers  urge  upon  them  to  study 
vigorously,  and  forget  their  discomforts,  and  that  the  good 
scholar,  who  is  anxious  for  his  lessons,  does  not  regard  these 
external  matters.     The  physical  sensations  will  come  first; 
they  will  have  the  first  care  of  the  brain  and  the  mind;  and 
it  is  only  by  great  mental  discipline  —  such  as  few  children 
possess  —  that  they  can  be  resisted  and  forgotten.     And  what- 
ever attention  these  suffering  children  give  to  the  physical 
sensations  is  manifestly  not  given  to  their  lessons. 

821.  The   same    incompatibility   exists   between  great  fa- 
tigue and  mental  labor.     While  the   nervous   energies    are 
devoted  to  restoring  power  to  the  muscles,  they  cannot  be 
given  to  thought  or  reflection.     The  boy  who   is  wearied 
with  hard  work  before  the  hours  of  school,  has  not  then  the 
free  command  of  his  brain  for  his  mental  action.     Very  la- 
borious men  are  apt  to  fall  asleep  when  they  take  up  a  book, 


BRAIN    AND    NERVOUS    SYSTEM.  357 

or  when  they  attend  to  a  lecture  or  to  a  sermon  in  church, 
especially  in  the  summer,  when  their  toil  is  the  most  ex- 
hausting. This  is  a  natural  and  necessary  consequence. 
The  mind  cannot  have  the  use  of  the  brain  when  it  is  occu- 
pied with  the  restoration  of  exhausted  physical  power ;  for 
there  is  only  a  definite  quantity  of  nervous  energy,  and,  if 
this  is  expended  in  muscular  action,  it  is  gone,  and  cannot 
be  given  to  mental  labor. 


CHAPTER    IX. 

Moral  Feelings  interfere  with  mental  Action.  —  Anxiety  and  Fear 
prevent  Attention  to  Business  and  Study.  —  Fear,  and  misdirected 
Hope,  improper  Motives  for  mental  Action. — Best  Motive. 

822.  THE  mind  cannot  give  its  full  and  undivided  atten- 
tion   to    observation    or   reflection  while  it  is  distracted  or 
disturbed  by  any  moral  feeling.     One  who  is  anxious  or  in 
fear   cannot  easily  study.     Hence  some  become  confused, 
and  lose  their  self-possession,  when  they  are  in  danger;  they 
do  not  then  cencentrate  their  thoughts,  and  see  clearly  the 
actual  circumstances  of  their  case,  or  the  means  of  relief. 
For  the  same  reason,  when  one  is  riding  with  an  ungovern- 
able  horse,  he  may  not  command  his  muscles  in  the  best 
way  for  his  safety.     Failing  to  perceive  his  true  condition 
and  means  of  escape,  so  as  to  direct  his  movements  to  this 
purpose,  he  may  do  the  very  things  that  increase.his  peril. 

823.  Anxiety  absorbs  much  of  the  energy  of  the  brain, 
and  prevents  mental  concentration ;  consequently,  one  can- 
not easily  study,  or  give  his  mind  to  ordinary  business,  while 
he  is  anxious  for  the  -life  of  a  parent  or  child,  who  is  danger- 
ously ill.     For  the  same  reason,  when  men  devote  themselves 
to  hazardous  speculations,  politics,  or  gambling,  they  often 
neglect  their  usual  engagements,  and  lose,  not  only  the  con- 
fidence of  their  employers,  but  even  the  power  of  successfully 
managing  their  customary  affairs. 


358  PHYSIOLOGY    AND    HEALTH. 

824.  The  action  of  the   same  principle  is  seen  in   the 
school-room.     When  the  boy  is  anxious  about  his  play,  or 
when  any  great  and    desirable  purpose  is  before  him,  and 
especially  if  it  be  a  matter  of  doubt  whether  he  shall  be  per- 
mitted to  enjoy  it,  his  lessons  may  suffer.     If  a  pleasant  ex- 
cursion is  proposed  for  the  afternoon,  provided  the  weather 
permit,  and  a  cloudy  forenoori  render  it  uncertain  whether 
a  rain  may  not  keep  him  at  home,  he  cannot  study  well  in 
this  fear.     The  attention  which  the  mind  gives  to  the  anxious 
doubt  must  all  be  at  the  cost  of  that  effort  which  otherwise 
might  have  been  devoted  to  his  books. 

825.  Whatever  may  be  the  kind  of  moral  feeling,  if  it  is 
strong,  and  absorbs  the  attention  and  power  of  the  brain,  it 
interferes  with  that  concentration  of  the  mind  that  is  neces- 
sary to  the  study  of  books,  or  learning  any  other  matters. 
The  homesick  boy,  away  from  home,  cannot  give  the  full 
energy  of  his  mind  to  his  books,  nor  even  to  any  labor.     An 
active  boy  was  sent  from  a  very  pleasant  home  to  learn  a 
desirable  trade  in  an  unpleasant  situation  and  unkind  family. 
Instead  of  giving  his  whole  thoughts  to  his  new  business,  he 
brooded  over  the  joys  and  comforts  .that  he  had  left  behind 
him  ;  his  heart  was  oppressed  with  sadness,  arrd  his  yearnings 
for  home  occupied  his  mind.     His  employer  thought  him  dull 
to  learn,  and  lazy  at  work;  and,  after  several  months  of  in- 
effectual trial,  by  common  consent  of  his    father    and    his 
master,  he  was  taken  away.     At  home,  he  again  manifested 
his  former  activity  and  desire  to  learn  the  same  trade,  and 
was  then   sent  to  another  and  more  satisfactory  place  and 
family,  where  every  thing  was  kind  and  encouraging.     He 
there  showed  great  interest  in  his  work,  learned  the  art  rap- 
idly, and  became  an  unusually  skilful  and  active  workman. 

82^.  There  are  some  seeming  contradictions  to  this  prin- 
ciple;  for  many  men  have  studied  and  become  accomplished 
scholars  when  oppressed  with  pecuniary  trials  or  bodily  pains. 
Some  of  the  best  works  in  the  language  were  written  under 
the  stimulus  of  poverty  ;  and  the  late  Robert  Hall  arose  from 
his  bed  of  acute  distress  to  preach  his  most  eloquent  and 


BRAIN    AND    NERVOUS    SYSTEM.  359 

powerful  sermons.  Some  are  so  absorbed  by  their  business 
or  anxiety  that  they  give  no  heed  to  impressions  that  would 
excite  physical,  and  even  painful  sensations;  while  thus  en- 
gaged, they  may  feel  neither  hunger  nor  cold,  and  forget  the 
hour  of  their  meals,  (§  87,  p.  46,)  or  their  chilled  flesh. 

827.  These  persons,  however,  are  exceptions  to  the  gen- 
eral law.     They  had  power  of  concentration  sufficient  to 
withhold  their  attention   from   the  causes    of  physical   and 
moral  suffering.     For  the  time,  they  forgot  their  painful  sen- 
sations, or  resisted  the  absorbing  influence  of  their  distress, 
and  concentrated  their  nervous  energies  upon  mental  action. 
They  have  extraordinary  power  or  discipline  of  mind,  or  are 
governed  by  an  extraordinary  motive  to  study  or  think  amidst 
such    counteracting    influences.      Nevertheless,    these    men 
bear  a  double  burden  —  one  in  the    disturbing  cause,  and 
the  other  in  the  intended  labor  of  the  brain ;  and,  though 
they  think  and  study  much,   they  could  do   more,  if  their 
minds  were  entirely  free. 

828.  It  requires  more  mental  discipline  to  study  amidst 
these  counteracting   or   disturbing   influences.     It  needs  a 
greater  power  of  the  will  over  the  feelings  to  abstract  the 
attention   from  all  that  would   excite    agreeable  or   painful 
sensations  or  emotions,  and  there  are  but  few  who  possess 
this  power  in  full  degree.     Yet  it  is  to  some  extent  neces- 
sary ;  .for,  though  one   can   study   better  when  the  body  is 
perfectly  easy,  and  the  mind  free  from  care,  and  the  heart 
from  pain,  yet  this  condition  is  not  always  attainable. 

829.  Even  the  motive  offered  as  an  inducement  for  action 
may  become  a  disturbing  cause,  and  absorb  so  much  of  the 
energy  of  the  brain  as  to  prevent,  in  some  degree,  the  very 
effort  it  was  designed  to  encourage.     In  this  respect,  both 
the  motive  of  fear  and  of  misdirected  hope  are  often  injuri- 
ous.    When  the  iron  rule  prevails  in  school,  the  boy's  con- 
stant fear  that  he  shall  be  caught  idle,  or  that  he  shall  fail  in 
his  lessons,  or  some  unexpected  accident  or  unpremeditated 
misdemeanor  may  happen  and  subject  him  to  punishment, 


360  PHYSIOLOGY    AND    HEALTH. 

makes  some  demand  upon  his  brain,  and  withdraws  so 
much  attention  from  the  subjects  which  he  is  required  to 
learn. 

830.  The  motive  of  misdirected  hope  and  of  undue  re- 
ward is  often  held  out  exclusively  as  a  stimulus  to  greater 
and  greater  mental  exertion.     Whenever  the  reward  does  not 
grow  naturally  and  necessarily  out  of  the  subject  of  study,  it 
may  interfere  with  its  own  purpose,  and  divide,  rather  than 
concentrate,  the  power  of  the  brain  and  the  attention  of  the 
mind.     If,  as  an  inducement  to  commit  a  lesson,  or  write  a 
legible  manuscript,  the  reward  of  a  silver  medal,  or  of  a 
book,  or  an  opportunity  of  declaiming  before  a  public  audi- 
ence,   is   proposed,    the    effect   of  division   of  thought   and 
weakening  mental  effort  follows. 

831.  But  the  motives  for  mental  exertion  which  belong 
to,  or  grow  out  of,  the  subject  to  be  studied,  not  only  with- 
draw- none  of  the  energies  of  the  brain  and  the  mind  from  the 
proposed  object,  and   therefore  neither  divide  nor  weaken 
their  exertions,  but  aid.  in  concentrating  all  their  force  upon 
the  single  point  of  study.     The  value  or  the  usefulness  of 
the  knowledge,  or  the  advantage  that  must   result  directly 
from  it,  and,  above  all,  the  mere  pleasure  of  learning,  are, 
therefore,  the  most  effective  motives  for,  and  auxiliaries  to, 
mental  labor.     For  this  reason,  boys  who  study  with  the  idea 
that  they  are  thereby  to  fit  themselves   for  usefulness,  re- 
spectability, and  happiness,    men    who  acquire  professional 
knowledge,  or  learn  science,  as  a  means  by  which  they  shall 
obtain  their  support,  or  fortune,  or  station,  or  do  good  to 
others     and,  above  all,  naturalists  and  others,  who  study  for 
the  love  of  the  sciences  to  which  they  give  their  attention,  — 
are  the  most  successful  scholars. 


BRAIN    AND    NERVOUS    SYSTEM.  361 


CHAPTER  X. 

Various  Powers  of  Mind.  —  Strengthened  by  Exercise.  —  Education 
adapted  to  Powers.  —  Education  of  Children.  —  Mind  cannot  be 
prematurely  strengthened.  —  Action  of  Brain  needs  Attention  to 
other  Organs.  —  111  Health  of  Students. 

832.  It  is  plain  that  there  are  various  faculties  of  the 
mind,  or  the  mind  has  power  of  application  to  various  pur- 
poses ;   and  the  commonest  observation  will  show  that  these 
faculties  are  not  equally  strong  in  all  persons.     As  the  mus- 
cular strength  is  unequally  distributed  to  the  several  limbs, 
so  the  mental  and  moral  power  is  unequally  distributed  to 
the  several  faculties  of  different  persons.     Thus  one  man  is 
strong  for  one  purpose  and  weak  for  another.     He  may  have 
a  genius  for  mathematics,  but  little  power  to  comprehend 
languages.     He  may  excel  in  music,  painting,  or  mechanics; 
he  may  be  a  skilful  machinist  or  financier,  and  make  great 
proficiency  in  any  one  of  these  subjects,  while,  in  all  others, 
he   may  not  be  above  the   average  of  men.     In  regard  to 
these,  as  well  as  all  other  subjects  to  which  the  human  mind 
is  applied,  there  is  a  great  difference  in  the  mental  power  of 
men.     This  difference  is  partly  native,  and  partly  the  re- 
sult of  education. 

833.  As  the  phyiical  powers  grow  and  become  strong  by 
proper  use  and  exercise,  and  as  any  one  of  these  becomes 
stronger  than  the  others  if  it  is  more  used  than  they  are,  so 
the  mental  and  moral  powers  may  be  strengthened  by  similar 
means.     All  proper  education  is  progressive,  and  is  adapted 
to  the  state  of  the  brain  and  mind  which  are  to  be  educated. 
It  begins  with  the  strength  and  knowledge  already  acquired, 
and  uses  these  as  the  means  of  acquiring  more.     Perfect  edu- 
cation brings  forth  and  strengthens  all  the  mental  and  moral 
faculties,  and  gives  them  equal  power.     If  these  are  original- 
ly unequal,  they  will  require  unequal  care  and  exercise  for 
their  development.     This  plan  of  education  of  the  various 
powers  is  also  adapted  to  the  natural  order  of  their  appear- 

31 


362  PHYSIOLOGY   AND   HEALTH. 

ance.  Tn  this  .order,  the  appetites  appear  first,  next  the 
muscular  power,  then  the  senses,  and  lastly  the  moral  and 
mental  faculties ;  and  a  person  successively  eats,  and  moves, 
and  observes,  and  reflects. 

834.  The  child  enjoys  the  use  of  his  senses.     He  wants 
things  visible    and   tangible.     His   perceptive  faculties    are 
developed  before  his  reflective.     He  observes  before  he  rea- 
sons.    He  learns  better  from  things  that  he  can   see  and 
touch,  than  from  descriptions  of  things  which  are  not  present 
to  his  senses.     He  can  better  give  his  attention  to  insects, 
flowers,  and  other  natural  objects,  than  to  any  abstract  prin- 
ciples of  which  he  may  not  see  the  application  or  the  use. 
When  these  simple  matters  are  taught,  and  the  child  learns 
the  uses  and  the  relations  of  such  things  as  he  can  see  and 
feel,  and  when  these  studies  are  sufficiently  varied  and  inter- 
changed with  muscular  exercise  and  recreation,  the  brain  is 
not  fatigued,  but,  on  the  contrary,  grows  stronger,  and  able 
to  undertake  higher  and  more  abstruse  matters. 

835.  In  early  life,  .the  brain  and  the  mind  are  feeble,  like 
the  other  organs  and  powers,  and  are  subject  to  the  same 
laws  of  exercise  and  rest.     Children  love  action,  but  they 
have  little  power  of  endurance.     They  dislike  to   confine 
their    attention   long   to   one   subject.     They    are   fond   of 
change,  for  a  variety  of  subjects  exercises  different  powers. 
They  are  soon  weary  of  one  kind  of  play  or  work,  and  want 
another;  they  like  to  change  their  studies  frequently;  they 
prefer  small  books  and  short  stories.     But  the  most  agreea- 
ble change  for  them  is  that  of  the  powers  arid  systems  which 
are  put  in  action.     They  love  to  use  the  brain  awhile,  and 
then  the  muscles,  and  then  these  both  together.     They  like 
to  study,  then  play,  then  work. 

836.  The  human  brain,  being  subject  to  the  same  laws 
that  govern  the  whole  physical  system,  cannot  be  premature- 
ly strengthened  and  applied  to  labor,  with  more  safety  than 
the  arm  or  the  stomach.     Its  growth,  from  the  earliest  in- 
fancy to   the  maturity    of  manhood,  is  naturally  slow    and 
gradual ;  and  it  would  be  as  injurious,  to  attempt  to  force  the 


BRAIN    AND    NERVOUS 

development  of  the  infant  mind,  or 
traordinary  exertions,  as  to  impose  upon  the  cl 
degree  or  weight  of  labor  beyond  its  years. 

837.  The  brain  and  nervous  system  of  most  precocious 
children  are  unusually  active;  but  often  they  are  stimulated 
by  injudicious  education.     In  these  cases,  the  nervous  ener- 
gies, that  should  sustain  the  nutritive  and  the  other  systems, 
are  absorbed  in  the   mental    Jabor.     The  mind  may  grow 
a  while  at  the  expense  of  the  physical  organs,  and  the  child 
make  great  advancement  in  learning;  but,  in  proportion  as 
the  brain  is  unnaturally  excited,  the  other  organs  are  deteri- 
orated, and  the  health  falters,  day  by  day,  and  the  child  may 
sink  in  death  from  over-stimulation  of  the  brain,  in  accord- 
ance with  that  universal  law  which  would  have  put  an  end 
to  life  if  the  stomach  or  the  muscles  had  been  unduly  ex- 
cited and  exerted  to  thasame  degree. 

838.  In  youth  and  manhood,  the  brain   cannot  work  long 
and  vigorously  without  the  health  of  the  rest  of  the  body. 
The  organs  are  all  linked  together,  and  dependent  one  upon 
another.     Each  must  have  its  due  supply  of  nervous  energy ; 
if  any  one  has  more  than  this,  —  if  it  be  stimulated  to  extraor- 
dinary exertion,  —  the  others  must  suffer.     Owing  to  inatten- 
tion to  the  physical  organs,  in  connection  with  mental  action,, 
many  students,  and  men  in  the  sedentary  professions,  suffer 
from  ill  health.     Ministers,  lawyers,  and  teachers,  are  fre- 
quently obliged,  from  this  cause,  to  suspend  or  give  up  their 
callings,  and  devote  their  whole  attention  to  the  recovery  of 
lost  health. 

839.  Health  fails  more  frequently  among  students  than 
among  men  in  the  more  active   employments.      More    men 
leave  college  or  quit  their  professions  than  leave  any  other 
callings  on  this  account.     This   ill    health    among  literary 
men  is  not  the  necessary  result  of  their  employments ;    it 
comes  from  the  irregular  distribution  of  the  nervous  power, 
and  want  of  due  cooperation  among  the  various  organs  and 
systems  that  go  to  sustain  life. 

840.  There  are  many  examples  of  the  happiest  and  most 


364  PHYSIOLOGY   AND    HEALTH. 

vigorous  longevity  in  the  pursuits  of  literature  and  science. 
Some  ministers,  lawyers,  arid  physicians,  have  attended  to 
their  professional  responsibilities  until  they  were  even  more 
than  fourscore  years  old.  Most  of  the  men  whose  vigor  and 
usefulness  were  thus  prolonged,  manifested  great  activity  of 
body,  as  well  as  energy  of  mind.  Their  mental  powers  were 
never  idle.  They  were  laborious  in  their  vocations,  and  stood 
among  the  foremost  as  scholars.  But  with  their  great  labor 
of  the  brain  they  judiciously  combined  due  attention  to  the 
other  organs  and  functions,  and  thus  sustained  their  physical 
health. 


CHAPTER   XI. 

Mental  and  physical  Powers  unequal  in  various  Persons.  —  May 
be  equalized  by  Education.  —  Inequality  of  mental  Powers  often 
increased  by  Education  and  Pursuits  of  Life.  —  Some  excel  in 
one  Thing  and  are  deficient  in  others ;  in  mechanical  Arts ;  in 
Morals.  —  Any  mental  or  moral  Power  may  be  developed  and 
strengthened. 

841.  In  some  persons,  the  several  systems  have  originally 
various  degrees  of  power.     The  nervous,  nutritive,  or  mus- 
cular system  may  be  strong  and  active,  while  the  others  are 
weak  and  inactive.     This  inequality  may  be  removed,  par- 
tially or  entirely,  by  judicious  training,  by  exercising  and 
strengthening   those   which    are    weak,    and    allowing    the 
stronger  to  rest.     For  this  purpose,  the  young  man  who  has 
naturally  strong  and  active  brain,  and  weak  muscles  and 
digestive  organs,  needs  the  exercise  of  physical  labor  for  his 
equal  development,  but  is  injured  by  much  mental  excite- 
ment ;  while,  on  the  contrary,  the  robust  and  vigorous,  whose 
brain  is  sluggish,  needs  the  stimulus  of  study,  and  can  bear 
the  physical  inaction  of  a  student's  life. 

842.  The  inequalities  of  the  mental  and  moral  powers 
may  be  removed  by  a  similar  principle  in  education,  which 
exercises   and   develops   the  weak,  and  leaves  the  stronger 
faculties  more  at  rest.     But,  by  a  mistake  in  the  purposes 


BRAIN    AND    NERVOUS    SYSTEM.  365 

of  education,  a  contrary  principle  is  often  adopted,  and  the 
strong  faculties  are  made  stronger  and  the  weak  weaker. 
Progress  and  acquirement  seem  to  be  the  great  object  with 
some,  and  therefore  they  apply  the  main  force  of  their  minds 
to  the  subjects  in  which  they  make  the  easiest  and  most  rapid 
advancement.  If  they  have  a  taste  for,  or  an  extraordinary 
power  of  understanding,  music,  mathematics,  mechanics,  or 
general  affairs,  they  give  their  attention  to  them,  and  neglect 
the  others,  for  which  they  have  less  taste,  and  which  they 
learn  with  difficulty. 

843.  Whatever  may  be  the  cause  that  only  a  part  of  the 
faculties  are  exercised,  and  the  others  dormant,  it  is  certain 
that  those  which  are  in  active  employment  will  be  quick  and 
comparatively    strong,   and    give  pleasure  when   in    action, 
while  the  others  are  slow  and  weak,  and  act  unwillingly,  and 
even  with  pain.     If  the  whole  force  of  the  brain  has  been 
directed  to  the  cultivation  or  the  action  of  one  or  a  few 
faculties,  the  dulness  and  weakness  of  the  others  are  about 
in  proportion  to  the  energy  and  activity  of  these.     Hence,  in 
the  division  of  labor,  a  man  becomes  a  more  perfect  work- 
man within  his  narrow  sphere;  but  his  range  of  knowledge 
is  limited. 

844.  Some  men  learn  and  perform,   during  their  whole 
lives,  only  one  operation  in  the  mechanic  arts.     In  this  lim- 
ited sphere  of  action,  they  show  exquisite  workmanship ;  but 
beyond  this  they  have  neither  knowledge  nor  power,  and  in 
the  subjects  of  general  interest  they  manifest  great  weakness 
and  inactivity  of  intellect.     In  the  manufacture  of  pins  there 
were  formerly  twenty  processes,  and  a  man  performed  only 
one  of  these.     From  the  beginning  to  the  end  of  his  working 
life,  he  exercised  only  the  faculty  of  making  one  twentieth 
part  of  a  pin,  and  if  required  to  do  any  other  work,  or  attend 
to  any  other  subject  of  thought,  he  did  it  unskilfully,  and 
with  reluctance. 

845.  The  same  is  shown  in  the  intellectual   processes. 
Some  men  cultivate  their  memory  to  a  remarkable  degree, 
without  a  corresponding  cultivation  of  the  reasoning  powers. 

31* 


36G  PHYSIOLOGY    AND    HEALTH. 

Their  minds  are  grand  storehouses  of  facts,  which  they  do  not 
know  how  to  apply  to  useful  purposes.  Some  have  great  rea- 
soning powers,  but  neither  carefully  observe,  nor  remember 
the  facts  that  are  presented  to  them.  Some  are  very  saga- 
cious in  some  kinds  of  business,  to  which  they  have  given 
particular  attention,  and  seem  lost  when  affairs  of  other 
kinds  are  presented  to  them. 

846.  The  moral  powers,  individually,  grow  or  suffer  by 
the  same  treatment.     If  cultivated,  they  are  strong  and  active  ; 
and,  if  neglected,  they  are  weak  and  sluggish.     Some  men 
are  rigidly  honest  and  sincere,  but  they  are  harsh  and  unkind. 
Others  are  the  very  reverse  of  these  —  gentle,  affectionate, 
and  full  of  benevolence,  while  they  fail  in  justice  and  truth. 
The  mind  may  be  so  exclusively  devoted  to  one  interest  as 
to  lose  sight  of  the  worth  of  others.     A  philanthropist  may 
be  so  intensely  absorbed  in  one  kind  of  human  distress  or 
one  means  of  relief,  as  to  think  all  othfer  sufferings  light,  and 
other  plans  of  relief  unworthy  of  notice. 

847.  In    any  time,  of  life,  the  weak    faculties    may    be 
strengthened,  and  the  strong  ones  made  stronger.     However 
difficult  any  mental  action  may  be  at  the  beginning,  it  be- 
comes familiar  and  easy  by  frequent  repetition.     The  faculty 
of  memory,  for  instance,  may  labor  hard  at  first,  but,  after  a 
time,  a  man  will  commit  pages  with  the  same  effort  that  he 
had  exerted  in  acquiring  as  many  lines.     A  young  minister, 
taking  charge  of  a  church  in  the  western  country,  —  where 
clergymen  usually  preach  without  notes,  —  and  yet  not  being 
accustomed  to  preach    extempore,  determined  to  write   his 
sermons,  and  then  commit  them  to  memory,  and  thus  avoid 
the  use  of  his  papers.     At  first,  it  cost  him  nearly  as  much 
labor  to  commit  as  to  write  his  sermons ;    but,  after  three 
years'  practice,  the  same  work  required  only  about  an  hour's 
attention. 

848.  The  power  of  observation  is  very  greatly  quickened 
and  strengthened  by  being  constantly  called  into  use.     One's 
eyesight  becomes  sharp,  and  he  learns  to  recognize  the  mat- 
ters which  he  looks  for.     The  practised  seaman  discovers  a 


BRAIN    AND    NEKVOUS    SYSTEM.  307 

sign  of  a  storm,  the  hunter  a  track  of  game,  and  the  botanist 
a  flower,  which  escape  the  notice  of  the  unpractised  ob- 
server. A  teacher  of  botany  carried,  in  June,  a  box  full  of 
new  flowers  to  a  new  but  zealous  pupil,  who  was  much 
gratified  with  the  sight  of  such  a  variety,  and  asked  where  he 
had  found  so  many.  "  On  the  road  to  the  mill."  «'  I  walked 
over  the  whole  of  that  road,"  said  the  scholar,  "  and  looked, 
as  I  thought,  carefully  for  flowers,  this  morning,  but  could 
find  only  two." 

849.  Any   one   or   more   of  the   moral   powers   may  be 
educated  in  the  same  manner.     Self-command  in  times  and 
scenes  of  peril  comes  by  education,  and  is  confirmed  by  habit. 
The  new  sailor  climbs  fearfully  to  the  mast,  and  has  hardly 
command  of  his  muscles  to  assist  in  the  management  of  his 
sails ;  but,  after  a  few  voyages,  the  same  man  will  run  over 
the  rigging,  and  work  there,  even  when  the  ship  is  violently 
rocked  in  the  storm,  with  as  much  self-possession  as  if  he 
were  working  in  a  shop  on  land.     A  painter's  young  appren- 
tice crawls  up  the  ladder  with  fearful  agitation,  and  uses  his 
brush  with  such  timid  caution  that  he  touches  over  only  a 
narrow  surface  on  either  side.     But  constant  practice  dis- 
pels all  fear,  and  then  he  runs  up  the  longest  ladder  without 
hesitation,  and  paints  on  either  side  to  the  farthest  reach  of 
his  arms. 

850.  In  this  development  of  the  moral  and  intellectual 
faculties,  teaching  is  the  guide,  and  shows  the  way,  and  no 
more ;  but  exercise  gives  them  power.     Learning  the  princi- 
ples alone  will  not  mak£  a  man  a  musician,  a  mechanic,  or 
a  philanthropist.     It  will  not  fill  his  heart  with  love,  cheer- 
fulness, or  self-denial.     The  brain  and  the  muscles,  the  mind 
and  the  hand,  must  be  accustomed  to  the  practice  of  these 
arts  and  principles,  in  order  to  make  one  skilful  or  virtuous. 
He  who  would  be  truly  benevolent,  must  accustom  himself 
to  do  kind  acts;  he  must  not  only  know  how,  but  he  must 
be    actually  employed   in   relieving   distress.     Cheerfulness 
must  be  established  by  the  same  practical  law.     Men  must 
not  only  believe  in  this  rule,  but  they  must  habitually  take 


368  PHYSIOLOGY    AND    HEALTH. 

cheerful  views  of  life,  and  always  look  hopefully  upon  the 
future. 

851.  True  politeness,  which  regards  others'  feelings,  and 
attends  to  their  wants,  becomes,  by  use,  so  ready  a  habit  as 
to  be  almost  a  part  of  our  nature.  No  principle  nor  motive 
can  supply  the  want  of  this  practice.  If  it  is  not  a  familiar 
habit,  the  politeness  is  artificial  and  awkward.  It  is  very 
easy,  in  company,  to  see  the  difference  between  the  cold  and 
ungraceful  manners  of  one  who  is  unkind,  and  selfish,  and 
clownish  at  home,  but  assumes  gentle  airs  in  society,  and 
the  easy  and  unassuming  manners  of  another,  who  is  ever 
the  same,  whether  at  home  or  abroad.  The  suavity  which 
is  assumed  only  for  the  public  eye  cannot  conceal  the  harsh- 
ness and  coarseness  of  domestic  habits. 


-CHAPTER   XII. 

Habitual  Actions  easy  and  agreeable.  —  Retired  People  averse  to 
general  Society.  —  Strength,  gained  by  Exercise,  preserved  by 
same  Means.  —  In  perfect  Men,  all  Powers  developed.  —  Concen- 
tration of  Mind.  —  Brain,  when  exhausted,  needs  Rest;  cannot 
be  overworked  advantageously.  —  Vacations  of  Schools. 

852.  HABITUAL  actions  are  not  only  easy,  but  agreeable ; 
but  those  actions  to  which  we  are  not  accustomed  exercise 
faculties  which  are  not  frequently  employed,  and  are  both  dif- 
ficult and  painful.     We  therefore  perform  them  unwillingly. 
For  this  reason,  many  men  prefer  to  associate  and  talk  with 
others  of  the  same  pursuits,  interests,  or  views  of  life ;  for 
conversation  with  them  calls  for  the  use  of  powers  that  are 
habitually  active,  and  association  with  men  of  different  char- 
acter would  call  for  the  use  of  powers  that  are  usually  dormant. 

853.  Men  who  are  unused  to  society  are  averse  to  gen- 
eral visiting,  because  miscellaneous    conversation    demands 
the  exercise  of  inactive  powers.     They  are  therefore  timid, 
and   fear   to  trust  themselves  in  the  discussion  of  subjects 
with  which  they  are  not   familiar,   and  in  which,  perhaps, 


BRAIN    AND    NERVOUS    SYSTEM.  369 

they  may  falter.  A  few  families,  living  in  a  retired*  district 
of  the  country,  have  associated  almost  exclusively  with 
each  other  for  two  or  three  generations,  and  have  had  very 
little  intercourse  with  the  world,  either  at  home  or  abroad. 
Their  exclusive  and  familiar  association  has  made  their 
conversation  upon  the  topics  and  interests  of  their  little 
neighborhood  easy  and  agreeable.  But  it  has  limifed  their 
ideas  and  feelings  to  their  vicinity.  Other  feelings  are 
dormant,  and  other  ideas  are  strange  to  them.  Conse- 
quently, conversation  with  men  from  other  places  calls  upon 
their  brain  to  attend  to  such  matters,  and  make  such  exer- 
tions, as  are  neither  familiar  nor  pleasant.  They  are,  conse- 
quently, timid  in  presence' of  strangers,  and  suspicious  of 
those  whose  habits  of  thought  and  notions  do  not  harmonize 
with  their  own. 

854.  The  strength  of  the  brain  and  the  mind,  or  of  any 
of  its  faculties,  which  is  gained  by  exercise,  must  be  pre- 
served by  the  same  means.     If  this  habitual  activity  of  the 
mental  or  moral  power  is  not  kept  up,  it  becomes  again 
weak.     The  musician  loses  his  skill,  and  the  accountant  his 
facility  of  reckoning,  when  out  of  practice.     The  bold  man 
in  danger   becomes  more  timid  after  living  a  long  time  in 
secure  places ;    the  bold  man  in  society  loses  his  self-pos- 
session when  he  retires  to  obscure  life;  and  the  hospitable 
man  entertains  his  friends  with  anxious  hesitancy  after  he 
has  ceased  to  keep  open  house. 

855.  As  in   the  perfect  body  all  the  organs  are  equally 
attended  to,  and  all  the  muscles  exercised,  so  in  the  perfect 
mind  all  the  mental  and  moral  faculties  are  developed,  exer- 
cised,  and    strengthened,   in    due  proportion.     Washington 
was  a  remarkable  instance  of  this  equality  and  completeness 
of  physical,    mental,    and   moral    character.     None   of  his 
powers  were  dormant,  and  none  had  excessive  growth.     All 
were  subject   to  the  control  of  his  will.     This  mental  and 
moral  fulness  and  discipline  give  men  command  of  their  re- 
sources,, and  great  power   in  every   emergency.     They  are 
thus  prepared   for  the  various  chances  of  life.     They  meet 


370  PHYSIOLOGY    AND    HEALTH. 

with  few  difficulties,  and  always  overcome  them.     They  are, 
therefore,  the  most  successful  and  the  happiest  men. 

856.  If  all  the  mental  faculties  are  faithfully  cultivated 
and  exercised,  the  mind  acquires  its  greatest  strength  and 
power   of  universal    application.      But  one   thing   more    is 
wanting ;   that  is,  the  power  of  concentrating  the  whole  men- 
tal energies  upon  a  single  subject,  to  the  exclusion  of  all 
others;  that  is,  the  power  of  the  will   over  all  the  physical 
organs,  over  the  instincts,  and  the  passions,  and  the  mental 
faculties. 

857.  This  mental  discipline  subdues  not  only  all  the  phys- 
ical and  moral,  but  the  mental  powers,  to  the  control  of  the 
will,  and  enables  us  to  concentrate  the  whole  force  of  the 
nervous  system  upon   one  object,   and   exclude   all   others ; 
otherwise,  the  mind  is  frequently  wandering  from  the  sub- 
ject proposed  to  it.     The  possession  or  want  of  this  control 
of  the  mind  —  this  power  of  concentration  —  constitutes  one 
great  difference  between  the  strong  and  the   weak  mind  — 
the  rapid  and  the  dull  scholar. 

858.  It  is  the   misfortune  of  many  students  that,  while 
they  fix  their  eyes  upon  their  books,  their  thoughts  are  afar 
off,  upon  their  play,  their  home,  or  their  pleasures.     They 
look  upon  their  lessons  in  school ;  their  eyes  run  over  a  page 
of  history  at  home ;  every  line,  every  word,  is  presented  to 
the  organ  of  vision ;  but  no  sensation  is  excited  in  the  brain, 
the  mind    receives  no  ideas.     Another,  with  better  mental 
discipline,  withdraws  his  mind  from  all  but  the  subject  before 
him ;  and,   while  he  is  reading  or  studying,    he  thinks  of 
nothing   else,  —  all    other  thoughts    are   excluded,    and  his 
whole  mental  force  is  directed  to  the  matter  about  which  he 
is  reading;  and  thus  he  loses  no  time,  and  wastes  no  mental 
effort.     Every  exertion  aids  him  in  his  advancement,  and  he 
is  therefore  a  successful  scholar. 

859.  The  brain  has  the  same  desire  and  enjoyment  of 
exercise  as  the  muscles.      The  child  runs  and  plays,   and 
observes  and  talks;  and  the  man,  if  he  has  no  occasion  for 
motion,  will  walk  for  exercise ;  and,  if  he  has  no  call  for 


BRAIN    AND    NERVOUS    SYSTEM.  371 

thought  or  observation,  he  will  yet  read,  —  perhaps  only  the 
lightest  books,  such  as  require  the  least  exertion  of  mind,  — 
or  he  will  talk,  if  of  nothing  more  important,  he  will  tell  of 
the  news  of  his  little  neighborhood,  or  he  will  sit  at  his 
window  and  watch  the  passengers  in  the  highway.  In  some 
way  or  other,  the  brain  is  frequently  exercised,  though  often 
m  the  gentlest  way.  There  are  few  who  sit  long  in  entire 
listlessness,  without  a  thought  or  an  emotion.  This  would 
be  as  painful  as  to  sit  immovably  still  for  any  considerable 
period,  without  moving  a  limb. 

860.  The  brain    has  the  same  liability  to   fatigue  from 
labor,  and  exhaustion  from  excess  of  exercise,  as  the  mus- 
cles.   It  has  a  definite  power  of  exertion,  beyond  which  it 
cannot  pass,  without  leaving  it  enfeebled.     If  its  action  is 
confined  within  this  due  limit,  and  sufficient  opportunity  is 
given,  at  proper  intervals,  for  its  recovery,  it  will  never  fall 
below  its  average  standard  of  effective  labor,  and  it  will  be 
able  on  each  day  to  do  a  full  day's  work.     But,  if  this  limit  is 
exceeded,  its  strength  is  reduced  so  far  below  its  own  stand- 
ard, that  it  is  not  recruited  in  the  allotted  time  of  rest,  and 
consequently  is  unable  to  perform  even  the  usual  work  on 
the  following  day. 

861.  A  gentleman  in  1842  had  occasion  to  write  several 
hundred  letters,  and  wished  to  finish  them  as  early  as  possi- 
ble.   With  the  average  industry  he  could  write  thirty  a  day, 
without  being  fatigued  beyond  the  power  of  the  night  to 
restore  his  mental  energies.     But,  feeling  over-anxious  to 
finish  the  work,  he  began  one  morning  at  six  o'clock,  and 
sat  at  his  desk  until  twelve  at  night.    Within  these  eighteen 
hours  he  wrote  fifty  letters,  and  then,  exhausted  in  mind,  he 
retired  to  rest,  but  did  not  readily  sleep  —  the  brain,  being 
much  excited,  was  not  easily  quieted.     The  next  day  he 
was  too  weary  to  write,  and  wrote  none.     That  day  was 
entirely  lost ;  and  even  on  the  third  day  he  fell  short  of  his 
thirty  lettersij_consequently  he  lost  more  than  he  gained  by 
this  vain  attempt  to  overwork  the  brain. 

862.  When  the  brain  has  thus  been  in  long  and  active 


372  PHYSIOLOGY    AND    HEALTH. 

labor,  its  excitement  does  not  subside  readily  with  the  cessa- 
tion of  work.  It  is  then  useless  to  attempt  to  sleep.  The 
nervous  energies,  thus  stimulated,  must  have  some  vent, 
either  by  light  reading,  conversation,  or  some  gentle  mus- 
cular exercise.  An  eminent  lawyer  in  Massachusetts,  who 
was  employed,  during  the  sessions  of  the  court,  in  an  almost 
continuous  succession  of  cases,  and  whose  brain  was  excited 
to  unremitting  labor  from  morning  till  late  at  night  during 
this  period,  found  it  impossible  to  sleep  immediately  after 
his  labors  ceased,  although  he  was  much  fatigued.  He 
therefore  accustomed  himself  to  walk  for  some  time,  after 
leaving  the  court-room  and  before  going  to  his  chamber. 
With  this  preparation,  he  slept  comfortably,  and  awoke  on 
the  following  morning  refreshed  and  prepared  for  renewed 
labor. 

863.  It  would  be  well  so  to  arrange  our  business  and 
studies,  that  the  brain  ^hould  be  required  to  work  and  ex- 
pend no  more  energy  in  each  day  than  it  can  recover  at 
night.  In  this  way,  it  would  be  able  to  perform  as  much  on 
the  day  following,  and  on  each  successive  day  thereafter,  and 
need  no  long  periods  of  rest  throughout  the  whole  of  life. 
But  this  is  not  usually  done.  Our  business,  our  schools, 
and  colleges,  are  arranged  upon  the  erroneous  plan  of  doing 
more  than  a  day's  mental  work  in  each  day  during  the  busy 
season  or  term  time,  and  of-having  intervals  of  rest  in  vaca- 
tions. This  arrangement  of  mental  action  and  rest  is  ordi- 
narily made,  not  in  reference  to  health  and  power  of  the 
mind  to  labor,  but  to  convenience,  or  pleasure.  Some  col- 
leges and  schools  have  long  terms  and  long  vacations,  to 
allow  the  pupils  to  visit  their  distant  homes.  The  mind  be- 
comes weary,  and  works  languidly,  in  the  latter  weeks  of 
these  long  terms,  and  the  habits  of  study  are  broken  up  in 
the  long  vacations;  and  neither  is  so  advantageous  for 
mental  action  and  health  as  short  and  more  frequent  periods 
of  labor  and  rest. 


BRAIN    AND    NERVOUS    SYSTEM.  373 


CHAPTER   XIII. 

Digestive  and  Mental  Powers  vary.  —  If  this  be  disregarded,  Diges- 
tive and  Mental  Disorder  may  follow.  —  Mind  disordered  by  Dys- 
pepsia; Cold;  Heat;  Over-Action 

864.  IT  is  well  known,  that  the  digestive  organs  are  not 
alike  in  all  persons.     One  cannot  eat  some  kinds  of  meat, 
another   cannot  digest  some  kinds  of  vegetables,  a  third  is 
sickened  with  some  kinds  of  fruit,  while    a  fourth  eats  of 
all  these,  and  obtains  nutriment  and  comfortable  health  from 
each.     So  long  as  these  persons  avoid  that  food  which  in- 
jures them,  they  eat  freely  and  maintain  their  health.     But, 
if  any  one   eats    that  which    he  does  not  digest  easily,  he 
suffers  from  pain ;  and,    if  he   perseveres    in  eating   it,  his 
stomach  becomes  deranged,  and  then  digests  nothing  easily. 

865.  So  it  is  with  the  mind,  which  is  not  equally  strong 
for  every  purpose.     If  its  attention  and  actions  are  confined 
to  the  purposes  which  it  can  accomplish,  and  if  it  avoids  all 
others  which  it  cannot  master,  it  manifests  no  disorder.     But 
when  it  is  required  to  attend  to  or  comprehend  such  subjects 
as  are  beyond  its   power,  or  assume  responsibilities  which 
are  impossible  for  it  to  bear,  it  struggles  to  do  this  with 
pain,  and  is  wearied  with  the  effort ;  and,  if  the  attempt  is  per- 
sisted in,  the   mind  is  weakened,  and  sometimes    becomes 
deranged. 

866.  Some  men  transact  their  usual  business,  and  fulfil 
their  responsibilities,  discreetly  and  successfully,  but  when 
they  go  out  of  their  ordinary  paths,  and  engage  in  political 
strife  or   religious     excitement,  or   when  they   suffer    from 
grief  or  from  the  unprosperous  turn  of  their  worldly  affairs, 
their  minds  lose  their  balance  and  become  deranged^    Many 
others  pass  through  the   same  excitements,  or  are  afflicted 
with  similar  troubles,  without  mental  disorder.     Those  who 
fall,  had  some  previous  weakness  of  mind  which  prevented 
their   enduring  what  the  others  endured  in    safety.     They 

32 


374  PHYSIOLOGY    AND    HEALTH. 

became   insane,   therefore,   in  circumstances  which  were 
harmless  to  their  associates. 

867,  The  immediate  sympathy  between  the  other  organs 
and  the  brain  compels  it  to  feel  their  ills,  and  to  be  often- 
times deranged  with  them.     Pains  of  the  head  and  confusion 
of  mind    are  connected  with  the  sickness  of  the   stomach. 
Insanity  sometimes  rises  from  dyspepsia.     In   such    cases, 
even  during  convalescence,  the  mental  disorder  is  brought 
back   by  renewal  of  the  digestive   trouble.     Any  error    in 
diet,    any  improper  food,    too  hearty  meals,   or  gas    in    the 
stomach,   excites  the  brain ;  then  the  old  delusions   again 
return,  and  the  mind  suffers  acute  distress  until  the  stom- 
ach is  relieved. 

868.  The  suppression  of  evacuations  to  which  the   sys- 
tem has  become  accustomed  sometimes  disturbs  the  brain, 
and   causes    mental    derangement.      Even    the   closing   an 
ulcer  which  has  been  .running  for  a  long  time  may  produce 
the  same  effect. 

86.9.'  Very  great  cold  confuses  the  brain,  and  deranges 
the  mind.  Captain  Parry,  in  the  journal  of  his  voyage  to 
the  Northern  Ocean,  states,  that,  when  his  men  were  exposed 
to  extreme  cold,  they  seemed  to  have  lost  their  power  of 
mind,  and  upon  one  occasion,  when  some  of  his  men  re- 
turned from  an  expedition  in  which  they  had  suffered  from 
great  severity  of  weather,  they  were  confused,  and  stared 
vacantly  and  wildly.  They  could  give  no  account  of  them- 
selves, nor  of  their  late  conduct;  but,  after  they  recovered 
their  natural  temperature,  they  regained  their  clearness  of 
intellect.  Similar  instances  are  given  in  Fremont's  journal 
of  his  second  expedition  over  the  Rocky  Mountains.  A 
high,  as  well  as  a  low  temperature,  usually  affects  the  mind 
unfavorably.  Mania  is  sometimes  caused  by  exposure  of 
the  head  to  great  heat. 

870.  Very  frequent  causes  of  insanity  are  connected  with 
the  abuses  of  the  mental  and  moral  powers.  As  dyspepsia 
arises  from  errors  in  diet,  —  from  the  wrong  purposes  to  which 
the  digestive  organs  are  applied,  or  from  the  excessive  bur- 


BRAIN    AND    NERVOUS    SYSTEM.  375 

dens  imposed  upon  them,  —  so  insanity  follows  the  wrong 
aoplication  of  the  powers  or  the  excessive  labors  of  the 
brain.  When  the  mind  is  required  to  attend  to  and  com- 
prehend subjects  beyond  its  powers,  or  manage  affairs  beyond 
its  control,  or  when  it  is  compelled  to  work  too  long  upon 
any  one  subject,  which  it  can  manage  to  a  moderate  extent, 
it  must  falter,  and  be  liable  to  irregular  action. 

871.  When  we  fix  the  eye  for  a  long  and  uninterrupted 
period  upon  any  single  object,  the  organ  becomes  weary,  and 
fails  to  receive  clear  impressions,  and  convey  them  to  the 
brain.  If  this  is  done  frequently  and  perseveringly,  the  eye 
becomes  weak  or  diseased,  and  ceases  to  perform  its  func- 
tions. In  the  same  manner,  the  brain,  by  over-exertion,  is 
wearied,  and  refuses  to  give  its  attention.  When  this  undue 
labor  has  been  continued  for  a  long  time,  without  proper 
intervals  of  rest,  the  mind  becomes  exhausted,  and  it  loses 
its  self-control  and  its  power  of  direction,  and  cannot  be 
roused  to  any  satisfactory  exertion.  It  is  then  permanently 
weak  and.  uncertain  in  its  operations. 


CHAPTER    XIV. 

Insanity,   from   misdirected   Education,  and   false   Hopes;  from  un- 
founded Expectations  j  religious  Anxiety  ;  perverse  mental  Habits. 

872.  MISDIRECTED  education,  the  preparation  for  pur- 
poses which  cannot  be  attained,  or  stations  which  cannot  be 
filled,  impose  upon  the  mind  an  excessive  burden,  and  in- 
volve it  in  a  profitless  struggle,  and  often  entail  upon  it 
weakness,  and  sometimes  disease.  All  wrong  notions  of 
life  necessarily  end  in  disappointment.  They  are  based 
upon  false  views  of  the  world  and  of  the  relations  of  society, 
and  lead  men  to  look  for  such  events  as  will  not  happen  in 
the  circumstances  which  must  surround  them.  The  flat- 
tered child  of  popular  favor,  who  expects  to  find  amid  the 


376  PHYSIOLOGY    AND    HEALTH. 

responsibilities  and  cares  of  riper  age  the  same  adulation 
and  caresses  that  come  to  the  careless  joyousriess  of  earlier 
years,  and  who  confidently  expects  that  the  future  will  bring 
him  a  measure  of  success  and  prosperity  for  which  he  is  not 
now  making  an  adequate  preparation,  must  meet  with  dis- 
appointment, and  suffer  the  consequences  of  sorrow  and 
perhaps  of  mental  disturbance. 

873.  All  those  expectations  which  are  founded  in  hope 
rather  than  on   calculation,  which  depend    upon  uncertain 
and  inappreciable  chances  for  their  gratification,  and  excite 
the  imagination  strongly,  must  often  fall  short  of  their  fulfil- 
ment.     Speculation  in  property  of  variable  value,  in  con- 
fidence of  great  profits ;  mining  in  those  regions  where  no 
human  sagacity  or  foresight  can  tell  whether  the  ore  can  be 
found,  or  obtained  at  profitable  cost ;  the  doubtful  struggle 
for  situations  of  honor  or  profit,  —  are  all  attended  with  great 
anxiety ;  and  when  they  fail,  as   they  frequently  must,  the 
spirit  sinks  and  the  mind  may  wander. 

874.  Religious  anxiety,  or  the  struggle  of  the  mind  in 
the  transition  from  old  to  new  conditions  or  opinions,   is 
occasionally    productive   of    mental    disorder.       When   the 
mind  has  given  up  the  old  foundations  on  which  it  rested 
its  hopes  and  its  confidence,  and  before  it  has  adopted  the 
new,  upon  which  it  can  securely  stand,  it  seems  to  be  un- 
loosed from  its  hold,  and  thrown  upon  uncertainty.     Persons 
in  this  condition   lose  their  self-control ;  the  world  and  its 
cares  and    enjoyments,   and   the    future,  with    its    promises 
and  its  threatenings,  change  their  aspect,  to  them,  and  they 
may  be  overwhelmed  with  distress.      If  then  they  can  see 
their   way    clearly   to   a  better  life,  the   excitement   passes 
away,  and  the  mind  is  easy ;    but    if  this    light    does   not 
appear  to  them,  they  may  fall  back  to  their    former  con- 
dition, or  become  a  prey  to  more  abiding  and  painful  de- 
rangement. 

875.  The  natural  appetites  may  be  so  pampered,  or  arti- 
ficial   appetites   may  be  created   and  may  grow  so  strong, 
that  we  cannot  control  them.     The  appetite  for  intoxicating 


BRAIN    AND    NERVOUS    SYSTEM.  377 

drinks  is  among  the  most  powerful  in  its  influence  over 
those  who  indulge  it.  This  is  not  a  natural  want.  It  is 
artificially  created  and  encouraged,  until  it  is  strong  enough 
to  take  care  of  itself  and  compel  its  gratification.  It  is  then 
in  vain  that  the  man  thinks  and  says,  he  will  not  desire  to 
drink ;  the  stomach  and  the  nervous  system  are  so  changed 
as  to  kindle  and  keep  up  this  burning  thirst  for  alcoholic 
stimulants.  The  man  may  have  moral  force  sufficient  to 
prevent  the  gratification,  but  one  may  as  well  say  that  the 
parched  tongue  of  fever  shall  not  be  dry  and  crave  cold 
water,  as  that  the  stomach,  excited  and  disordered  by  in- 
temperance, shall  not  thirst  and  crave  its  accustomed  in- 
dulgence. 

876.  The  irregular  habits  of  the  mind  sometimes  over- 
power the  will.  Some  individuals  exhibit  a  propensity  to  do 
strange  things,  and  to  utter  startling  opinions.  They  have  a 
fondness  for  attracting  attention  by  their  oddity  of  manners, 
or  thoughts,  or  language.  At  first,  these  singularities  are 
assumed  and  put  off  at  pleasure ;  but,  if  they  are  allowed  to 
come  often,  they  establish  a  habit  which  cannot  be  resisted. 
The  man  is  then  compelled  to  exhibit  his  oddities  at  times 
when  he  would  be  glad  to  appear  like  other  people.  In 
other  matters,  his  brain  and  his  mental  operations  may  be 
manageable,  and  he  may  be  sound  in  mind ;  but  so  far  as  he 
cannot  or  does  not  regulate  his  thoughts,  his  mind  is  not 
sound. 


CHAPTER  XV. 

Day-Dreaming.  —  Fits  of  Passion.  —  Intoxication.  —  Fright  may 
cause  Insanity.  —  Various  Grades  of  mental  Health  between  Sani- 
ty and  Insanity. —  No  sound  Mind  without  sound  Body.  —  Most 
Causes  of  mental  Disorder  within  our  Control. 

877.    SOME  take  great  pleasure  in  day-dreaming.     They 
Jove  to  abstract  their  minds  from  the  facts  and  things  about 
them,  —  from  subjects  of  real  existence,  —  and,  creating  an 
32* 


378  PHYSIOLOGY    AND    HEALTH. 

imaginary  world,  surround  themselves  with  a  train  of  circum- 
stances from  which  unpleasant  things  shall  be  excluded,  and 
nothing  but  the  agreeable  be  near  them.  In  such  a  world, 
they  determine  what  they  would  do  and  say,  what  principles 
should  govern  them,  and  what  impressions  they  would  make 
upon  their  associates.  Thus  they  revel  in  this  delightful 
revery,  where  all  is  beautiful  and  satisfactory. 

878.  This  habit  of  revery  grows  more  easy  and  inviting, 
so  that  the  mind  insensibly  falls  into  it  when  not  otherwise 
occupied.     Then  the  will  loses  its  power  to  exclude  it,  and 
direct  the  thoughts  to  the  mixed  realities  of  life,  until,  at  last, 
the  dreaming  becomes  irresistible,  and  the  dreamer  can  no 
longer  control  his  wandering  mind,  nor  see  things  as  they 
are.     For  a  period,  —  perhaps  for  years,  —  he  governs  his 
imagination  in  presence  of  others,  and  conceals  his  dreams 
from  the  world.      But  the  habit  grows  stronger,  and  finall), 
regarding  neither  men  nor  circumstances,  it  will  speak  out; 
and  when  the  dreamer  talks  as  he  thinks,  and  uses  strange 
language,  and  perhaps   exhibits  strange  conduct,  he  is  ac- 
knowledged insane. 

879.  When  the  mind  has  been  strongly  excited,  the  law 
of  continuance  prevents  its  immediate  return  to  rest,  and  we 
think  of  those  matters  that  intensely  interested  us,  after  the 
time  of  their  action  has  passed  away.     We  cannot  dismiss 
immediately  strong  sensations,  and  feelings,  and   thoughts; 
and,  if  they  were  violent,  they  may  remain  for  a  long  period. 
The  agitation  of  fright  continues  after  the  cause  is  removed. 
As  blindness,  partial  or  total,  may  arise  from  the  glare  of 
intense  light,  so  the  mind,  when  confused  with  terror,  or  dis- 
turbed with  powerful  irritation,  may  not  recover  its  clear- 
ness and  self-control,  but  remain  disordered. 

880.  Men  under  the  excitement  of  passion  lose  their  self- 
control,  and  perform  acts,  and  give  utterance  to  language, 
which,  in  their  calm  moments,  they  would  not  willingly  al- 
low in  themselves.    If  these  passionate  excitements  are  not 
checked,  they  gain  more  and  more  power  to  subdue  the  will, 
while  the  resolution  to  resist  grows  weaker.     Gradually,  the 


BRAIN    AND    NERVOUS    SYSTEM.  379 

•objection  of  the  will  to  the  excited  feelings  increases,  the 
mind  is  made  insane  from  slighter  causes,  and  the  derange- 
ment is  longer  continued,  until  this  disorder  is  fixed,  and  the 
passionate  man  is  a  maniac. 

881.  Whether  the    brain    be  unduly  excited   by  mental 
action,  or  by  any  physical  stimulant,  the  result  is  the  same  — 
mental   derangement.     Intoxication  with    alcohol   creates  a 
powerful  operation  on  this  organ,  which  is  plainly  an  irregu- 
lar and  uncontrollable  one.     The  drunken  man  has  no  more 
power  over  his  thoughts  than  the  maniac.     Usually,  after  a 
fit  of  intoxication  passes  away,  the  brain  recovers  its  self- 
possession,  and  the  mind  is  restored  to  health ;   yet  some- 
times this  complete  restoration  does  not  take  place,  and 
the  mind  cf  the  drunkard  continues  weak  and  irregular  in 
its  action,  and  he  is  then  a  lunatic. 

882.  It  is  not  to  be  supposed  that  all  these  causes  pro- 
duce insanity,  or  that  this  disease  must  always  follow  these 
violations  of  the  njitural  laws.     But  there  is  a  wide  differ- 
ence between  the  clear  and  well-disciplined  mind,  that  can 
be  directed  at  will,  and  understand  and  reason  correctly, 
and  is  buoyant  with  cheerfulness,  and  the  mind  that  is  to- 
tally deranged  with  lunacy,  or  overpowered  with  melancholy. 
And   in   this   wide   interval   there  are   all   grades  of  mental 
health  and  power.     The  mind  that  is  excited  with  alcohol 
or  passion,  or  depressed  with  fear,  is  incapable  of  the  clearest 
perceptions  of  the  true  and  the  reasonable.     The  brain  that 
is  torpid  after  an  excessive  dinner,  or  that  is  in  pain  from 
dyspepsia,  is,  for  the  time  being,  deprived  of  its  full  power 
of  action.     Anxiety,  grief,  disappointment,  and  day-dream- 
ing, absorb  some  of  the  nervous  power,  and  prevent  the  free 
and  untrammelled  range  of  thought.     These,  and  all  other 
habits   and   conditions  that  diminish  or   absorb  any  of  the 
nervous  energy,  so  far  as  they  lay  any  tax  upon  the  strength 
or  the  labor  of  the  brain,  or  interfere  with  its  free  operations, 
oppress  or  excite  the  mind. 

883.  It  will  now  be  plainly  seen  that  there  is  no  sound 
ness  of  mind  without  a  sound  brain,  and  that  disorder  of  an) 


380  PHYSIOLOGY    AND    HEAXTII. 

or  all  of  the  other  organs  may  derange  the  nervous  system, 
and  produce  mental  derangement.  It  is  also  manifest  that 
the  abuse  or  neglect  of  any  of  the  passions,  propensities,  or 
mental  faculties,  may  produce  the  same  result,  in  greater  or 
less  degree,  of  disordered  mind.  Most,  if  not  all  the  causes 
of  partial  or  total  insanity,  come  within  our  cognizance,  and 
are  originally  within  our  control.  The  brain  and  the  mind 
are  as  subject  to  fixed  laws  as  the  other  organs,  and  it  is  left 
for  us  to  see  that  the  conditions  of  their  life  are  fulfilled, 
and  that  we  enjoy,  not  only  general  and  open  mental  health, 
but,  under  every  circumstance,  and  in  every  moment  of  our 
lives,  in  secret  as  well  as  in  public,  we  possess  full  mental 
strength,  and  the  clearest  power  of  thought,  and  the  most 
perfect  control  over  our  feelings  and  passions. 


EYE. 
CHAPTER   XVI. 

Eye.  —  Situation.  —  Composition.  —  Humors.  —  Lens.  —  Coverings. 
—  Iris.  —  Pupil.  —  Effect  of  Light.  —  Lids.  —  Tears.  —  Lachrymal 
Apparatus.  —  Muscles.  —  Cross-eye.  —  Optic  Nerve. 

884.  The  eye  is  placed  in  a  deep,  bony  socket  in  the  skull. 
This  socket  extends  far  backward  at  the  base  of  the  brain, 
and  defends  this  tender  organ  from  blows  and  accidents  on 
every  side  except  the  front. 

885.  The  eyeball  is  composed  of  three  substances. 

The  aqueous,  or  watery  humor,  (Fig.  LXVI.  b,}  is  a  clear, 
transparent  fluid,  and  stands  in  the  front  of  the  eye. 

The  vitreous  humor  forms  almost  the  whole  of  the  globe, 
(Fig.  LXVI.  d.)  This  is  a  transparent  substance,  and  soft  like 
a  jelly.  It  is  enclosed  in  a  very  delicate  membrane,  which 
covers  its  outside,  and,  extending  through  it,  forms  many 
cells,  which  contain  this  humor. 


EYE.  381 

The  crystalline  lens  stands  between  the  vitreous  and  the 
aqueous  humors,  (Fig.LXVI.  c.)  This  is  a  double  convex 
lens,  much  more  dense  than  the  vitreous  humor,  and  holds  its 
shape  without  any  covering.  It  is  composed  of  concentric 

FIG.  LXVI.    Section  of  the  Eye. 

a,  Coats  of  the  eye. 

b,  Aqueous  humor. 

c,  Crystalline  lens. 

d,  Vitreous  humor. 

e,  Cornea. 
/,/,  Iris. 

g,  Optic  nerve. 
h,  Retina. 

layers  like  those  of  an  onion,  which  can  be  removed  one  from 
another.  In  the  fish,  this  lens  is  globular.  In  man,  it  ap- 
proaches flatness. 

886.  Three  membranes  or  coats  enclose  these  humors,  and 
retain  the  eye  in  its  globular  shape. 

The  outer,  or  sclerotic  coat,  like  the  dura  mater  of  the 
brain,  is  very  firm  and  strong,  and  able  to  resist  considerable 
force  without  being  broken.  It  covers  almost  the  whole  eye. 
It  has  a  large  aperture  in  front,  in  which  the  cornea  is  placed, 
(Fig.  LXVI.  e.)  The  cornea  covers  the  front  of  the  eye.  It  is 
transparent  and  strong.  It  projects  in  the  shape  of  a  watch 
glass,  and  covers  the  aqueous  humor. 

887.  The  middle,  or  choroid  coat  of  the  eye  is  very  delicate 
and  soft.     It  contains  a  black  pigment,  which  absorbs  such 
rays  of  1  ight  as  are  not  needed  for  vision. 

888.  The  third  or  inner  coat  is  the  retina^  which  is  prin- 
cipally the  expansion  of  the  optic  nerve.     This  receives  the 
rays  of  light  from  the  objects  which  are  presented  to  the  eye. 

889.  In  the  front  part  of  the  eye  are,  1st.  The  cornea. 
2d.  The  aqueous  humor.     3d.  The  iris  and  pupil.     4th.  The 
crystalline  lens,  and  then  the  vitreous  humor. 

The  iris  is  a  very  delicate  circle,  or  continuation  of  the 
middle  or  choroid  coat,  (Fig.  LXVI.  f^f.)  The  pupil  is  an 


382  PHYSIOLOGY    AND    HEALTH. 

aperture  in  the  centre  of  the  iris.  The  iris  is  expansible  and 
contractile:  when  it  expands,  it  extends  toward  the  centre, 
and  lessens  the  diameter  of  the  pupil  ;  and  when  it  contracts, 
it  draws  back  from  the  centre,  and  enlarges  the  pupil.  By 
this  means,  the  amount  of  light  received  into  the  eye  is  regu- 
lated. When  we  are  in  a  dark  place,  the  iris  contracts,  the 
pupil  is  enlarged,  and  more  rays  are  admitted.  When  the 
light  is  increased,  the  iris  expands,  the  pupil  is  contracted, 
and  fewer  rays  are  admitted.  When  we  first  go  from  a  bright 
light,  as  from  a  well-lighted  room  to  the  darker  air  abroad  in 
the  evening,  we  see  with  difficulty,  because  the  pupil  is  so 
small  that  few  rays  can  enter  the  eye.  But  soon  the  pupil 
enlarges,  more  rays  enter,  and  we  see  with  ease.  On  the 
contrary,  when  we  go  suddenly  from  a  dark  to  a  very  light 
place,  the  pupil  being  large,  much  light  enters,  and  the  eye& 
are  dazzled  ;  but  soon  the  iris  expands,  the  pupil  diminishes 
and  fewer  rays  enter,  and  we  bear  the  light  without  incon 
venience. 

899.  The  lids  protect  the  eyes  in  front.  They  are  corn 
posed  of  cartilages  adapted  to  the  shape  of  the  eye,  the  skin 
without,  and  the  lining  membrane  within.  The  lining  of  the 
lids  is  continued  over  the  front  of  the  eye.  It  prepares  and 
throws  out  upon  itself  a  thin  mucous  or  glairy  fluid,  that  oils 
the  surface  and  allows  the  lids  to  glide  smoothly  over  the  ball. 
One  circular  muscle  surrounds  the  open  part  of  the  eye,  (Fig. 
Lil.  ft,)  and  closes  the  lids  when  it  contracts.  Another  mus- 
cle, attached  to  the  upper  eyelid  by  one  end,  and  to  the  bone 
of  the  socket  by  the  other,  opens  the  eye. 

891.  The  tears  wash  the  eye  and  keep  its  surface  dean. 
The  apparatus  for  this  purpose  consists  of  the  lachrymal 
glands,  tubes,  ducts,  and  canal.  The  lachrymal  glands  are 
placed  in  the  upper  and  outer  corner  of  the  socket,  (Fig. 
LXVII.  a.)  They  prepare  the  tears,  which  then  flow  through 
the  ducts  (Fig.  LXVII.  ft)  under  the  upper  lid  into  the  eye.  By 
the  motions  of  the  lids  the  tears  are  spread  over  all  the  surface 
of  the  eye,  and  wash  away  any  particles  of  dust.  Then  they 
fall  into  a  little  groove  or  trough  in  the  upper  edge  of  the 


EYE.  383 

lower  lid,  and  flow  along  to  the  inner  corner  of  the  eye.  There 
they  are  received  through  very  small  apertures  into  the  lach- 
rymal canals,  and  then  they  pass  through  the  nasal  duct  (Fig. 
LXVII.  d,  d)  into  the  nose. 

FIG.  LXVII.    Lachrymal  Apparatus. 


a,  Lachrymal  gland. 

b,  Lachrymal  ducts. 

c,  c,  Lachrymal  canals. 

d,  d,  Nasal  duct. 


892.  The  lachrymal  canals  are  sometimes  inflamed  and 
closed,  and  the  passage  for  the  tears  into  the  nose  is  thus 
stopped.     The  tears  then  find  no  outlet,  and  flow  over  upon 
the  cheek,  causing  some  irritation. 

893.  This  apparatus  sympathizes  with  the  moral  affections. 
The  tears  are  prepared  in  the  gland,  and  flow  more  abun- 
dantly than  they  can  be  received  in  the  canals,  in  grief,  and 
sometimes  in  joy,  and  then  they  flow  over  the  cheeks. 

894.  The  eye  is  rolled  by  a  set  of  muscles  peculiar  to  itself. 
These  are  attached  by  one  end  to  the  bony  socket,  and  by  the 
other  to  the  eyeball.     By  their  contractions  they  roll  the  eye 
in  every  direction  ;  and,  by  their  cooperation,  both  eyes  are 
directed  to  a  single  object. 

895.  In  cross-eyed  persons,  these  muscles  do  not  work  in 
harmony  ;  some  one  acts  more  powerfully  than  the  correspond- 
ing muscles,  and  draws  one  eye  to  one  side  more  than  the 
other :  this  is  most  commonly  inward. 


384 


PHYSIOLOGY    AND    HEALTH, 


896.  The  optic  nerve  (Fig.  LXVI.  g)  passes  from  the  base 
of  the  brain  forward  through  the  socket  and  into  the  eyeball. 
After  passing  the  outer  and  middle  coats,  it  is  spread  out  on 
their  inner  surface,  and  forms  the  retina,  which  receives  the 
rays  of  light. 

FIG.  LXVIII.    Muscles  of  the  Eye. 


«,  Part  of  the  bony  socket. 

b,  Optic  nerve. 

c,  Eyeball. 

d,  Muscle  that  raises  thie  upper 
lid. 

e,  g,  Muscle  that  passes  from 
the  socket  at  a,  through  the  loop 


/,  and  back  to  the  ball.  It  rolls 
the  eye  downward  and  outward. 
h,  Muscle  attached  to  outer 
edge  of  the  bony  socket,  and  to 
the  side  of  the  ball.  It  rolls  the 
eye  upward  and  inward. 


897.  The  eye  is  thus  complicated,  with  many  and  various 
parts,  all  of  which  are  arranged  and  harmonized  together, 
and  all  acfapted  to  the  action  of  light  without,  and  to  the  per- 
ceptive power  of  the  brain  within. 

The  light  is  reflected  from  objects,  and  passes  through  the 
transparent  cornea  and  the  pupil  into  the  ball.  The  humors 
and  the  lens  refract  these  rays,  and  give  them  such  a  direction 
that  they  fall  upon  the  retina,  where  they  form  the  image  of 
the  object.  This  impression  is  carried  along  the  optic  nerve 
to  the  brain,  and  there  perception  takes  place  and  the  object 
is  seen. 


EYE.  385 


CHAPTER    XVII. 

Near-sightedness.  —  Spectacles  to  be  worn  cautiously.  — Eye-Glaasea 
injurious.  —  Far-sightedness. — Eye  suffers  with  other  Organs.— 
Needs  Cleanliness.  —  Bathing.  —  Pure  Air.  —  Sufficient  Light.  — 
Best. 

898.  THE  eye  is  subject  to  very  many  and  various  derange 
ments,  which  impair  vision  in  various  ways  and  degrees. 

Near-sightedness  is  one  of  the  most  common  defects  of  vis- 
ion. This  arises  from  various  causes.  It  is  most  frequently 
produced  by  the  habit  of  looking  at  very  near  objects  ;  as  in 
reading,  writing,  engraving,  sewing,  &.C.,  when  the  books, 
papers,  or  work  are  held  close  to  the  eye.  In  persons  so  em- 
ployed, the  eye  so  habitually  adapts  its  focus  to  these  near 
objects,  that  it  is  difficult,  or  even  impossible,  to  adapt  it  to 
objects  at  a  greater  distance. 

This  defect  may  be  avoided  or  lessened  by  being  much 
abroad  and  accustoming  the  eye  to  look  at  distant  objects, 
landscapes,  scenery,  &c.,  and  also  by  holding  the  books  or 
the  work  as  far  from  the  eye  as  possible. 

899.  In  this  disorder,  the  lenses  are  supposed  to  be  too 
round.     They  refract  the  rays  too  much,  and   concentrate 
them,  and  form   the  image,  before   they  reach   the   retina. 

Concave  spectacles  obviate  near-sightedness.  They  give  a  dif- 
ferent refraction  to  the  rays,  and  throw  the  image  upon  the  ret- 
ina. When  they  are  used,  and  especially  when  they  are  worn 
constantly,  the  eye  makes  no  effort  to  accommodate  its  focus 
to  distant  objects,  and  remains  permanently  near-sighted,  and 
frequently  the  difficulty  is  increased.  But  if  spectacles  are 
omitted  as  long  as  possible,  and  then  used  only  occasionally  and 
for  seeing  distant  objects,  leaving  the  eye  to  its  own  resources 
for  all  near  and  household  objects,  the  evil  would  not  tend  to 
increase,  and  the  eye  would  enjoy  a  wider  range  of  vision. 

900.  Spectacles  covering   both  eyes  affect  them  equally, 
and  give  them  the  same  focus.     But  eye-glasses  being  used 
for  only  one  eye,  makes  that  more  near-sighted  than  the  other 
and  these  organs,  therefore,  have  unequal  power  of  vision. 

33 


386  PHYSIOLOGY   AND    HEALTH. 

901.  Far-sightedness  is  a  defect  of  age,  when  the  eye  loses 
the  power  of  adapting  its  focus  to  near  objects.     The  lena 
loses  its  convexity  in  some  degree,  and  the  rays  are  not  con- 
centrated upon  the  retina.     This  evil  is  obviated  by  the  use 
of  convex  glasses,  which  give  the  rays  the  proper  refraction, 
throw  the  image  upon  the  retina,  and  enable  the  eye  to  see 
near  objects  distinctly, 

902.  The  eye  suffers  with  the  rest  of  the  body.     The  sight 
is  best  in  vigorous  health,  and  is  impaired  by  many  diseases. 
Some  disorders  of  the  eye  have  their  origin  solely  in  dis- 
orders in   distant  organs.     A   troublesome  affection,  called 
muscce  volitantes,  or  flying  flies,  is  sometimes  caused  by  in- 
digestion merely.     The  dyspeptic  then  sees  flies  or  motes,  or 

•little  clouds,  that  seem  to  be  flying  before  his  eyes.  These 
are  owing  to  the  state  of  the  retina,  which  is  frequently  caused 
by  the  state  of  the  digestive  organs ;  and  when  the  stomach 
is  restored  to  health, -the  flying  flies  are  gone. 

903.  The  eye  wants  the  utmost  cleanliness  for  its  health. 
It  should,  therefore,  be  bathed  and  kept  free  from  dust  and 
other  matters.     It  is  benefited  by  the  bath  as  well   as  the 
skin.     It  is  well  to  dip  the  face  every  morning,  with  the  eyes 
open,  in  cold  and  clear  water,  and  then  to  move  the  lids  and 
thus  wash  the   surface.     This   should  be  done   daily,  and 
oftener  when  exposed  to  dust  or  other  offensive  matters. 

904.  The  eye  needs  fresh  and  pure  air.     Those  who  live 
in  the  foul  air  of  crowded  dwellings  and  shops,  or  in  the 
smoke  of  some  rooms,  often  have  disordered  vision. 

905.  The  eye  is  made  for,  and  should  be  accustomed  to,  the 
light.     Those  who  work  in  dark  shops,  or  live  in  dark  streets 
or  houses,  or  in  parlors  closely  darkened  with  curtains  and 
blinds,  and  women  who  wear  veils  to  shut  out  the  free  light 
of  day,  have  comparatively  weakened  vision. 

906.  The  eyes  need  light  for  vision,  and  suffer  or  lose  their 
power  in  some  degree  when  required  to  labor  in  insufficient 
light.     Thus  they  are  injured  when  used  for  reading,  sewing, 
or  examining  any  minute  objects  by  twilight  or  moonlight,  or 
in  any  insufficient  light,  by  day  or  night.     All  imperfectly 


EAR.  387 

ighted  apartments,  counting-rooms,  houses  and  shops  in  dark 
alleys,  or  with  insufficient  windows,  weaken  the  vision  of 
those  who  study,  write,  or  work  in  them. 

907.  The  eyes  suffer  from  protracted  exertion  in  the  same 
way  as  the  brain  and  the  muscles.  They  become  wearied, 
and  even  sometimes  disordered,  from  looking  long  at  objects 
that  require  minute  attention,  as  reading  fine  print,  engraving, 
miniature  portrait  painting,  sewing,  &c.  Those  who  are 
employed  in  such  things  would  do  well  to  give  their  eyes 
change  of  occupation  and  rest. 


EAR. 

CHAPTER  XVIII. 

Composition.  —  External  Ear.  —  Position.  —  Not  to  be  covered.  — 
Ear- Wax.  —  Membrane  of  the  Tympanum.  —  Eustachian  Tube. — 
Bones  of  the  Ear.  —  Labyrinth.  —  Nerve.  —  Requisites  of  hearing. 
—  Air.  —  Healthy  Ear.  —  Attention.  —  Deafness.  —  Causes.  —  Hear- 
ing may  be  cultivated.  —  Ear  for  Music. 

908.  THE  organ  of  hearing  includes  the  external  ear,  which, 
is  on  the  outside  of  the  head,  the  passage  to  the  tympanum  or 
drum,  and  the  internal  ear,  which  is  within  the  drum. 

909.  The  outer  ear  is  composed  principally  of  a  somewhat 
stiff  cartilage,  that  retains  it  in  its  shape. 

The  shape  of  the  outer  ear  is  that  which  is  best  adapted  to 
catch  sounds  and  transmit  them  to  the  internal  ear.  This 
form  has  been  adopted  by  skilful  mechanicians,  to  gather 
sounds  in  rooms  and  transmit  them  to  other  and  distant 
places. 

The  ears  of  the  lower  animals  are  differently  shaped,  accord- 
ing to  their  different  purposes.  The  human  ear  is  scarcely 
movable ;  but,  in  some  other  animals  it  is  moved  to  catch 
rounds  in  different  directions. 


388 


PHYSIOLOGY    AND    HEALTH. 


910.  TJie  human  ear,  in  its  natural  condition,  stands  out 
from  the  head  at  a  considerable  angle.    This  position  gives 
it  the  greatest  advantage  for  catching  sounds.    Uut  the  cus- 
tom of  wearing  caps  and  other  head  dresses,  and  the  manner 
of  dressing  the  hair,  press  the  ear  near,  and  in  some  persons 
close  to,  the  head,  and   thus   diminish   their  acuteness  of 
hearing. 

911.  The  entire  external  ear  stands  open  for  the  reception 
of  sounds  ;  but  when  any  of  its  parts,  or  the  whole,  is  covered 
with  the  hair  or  any  dresses,  the  access  of  sound  is  obstructed, 
and  the  hearing  somewhat  impaired. 

Fm.  LXIX.    Ear. 


a,  a,  External  Ear. 

5,  Opening  to  the  internal  ear. 

c,  Canal  leading  to  the  drum. 

d,  Membrane  of  the  tympanum. 

e,  Semicircular  canals. 
/,  Snail-shell,  or  cochlea. 


912.  The  external  canal  or  meatus,  (Fig.  LXIX.  c,)  opens 
from  the  external  to  the  internal  ear.     It  is  about  an  inch 
long.     Its  course  is  not  straight  nor  direct,  but  somewhat  for- 
ward and  curved.     There  are  many  little  cells  in  its  lining, 
in  which  the  ear-wax  is  prepared.     There  are,  also,  hairs 
about  this  canal.     The  wax  and  the  hairs  protect  this  canal 
from  the  entrance  of  insects. 

The  ear-wax  is  sometimes  secreted  in  so  great  quantity  as 
to  fill  the  canal,  and  prevent  the  access  of  sound. 

913.  The  membrane  of  the  tympanum,  or  covering  of  the 
drum  of  the  car,  is  spread  across  the  bottom  of  the  canal  and 


EAE.  389 

closes  it.    This  very  delicate  membrane  separates  the  canal, 
or  middle-ear,  from  the  internal  ear. 

914.  The  cavity  of  the  internal  ear  is  behind  the  membrane 
of  the  tympanum.     This  cavity  is  filled  with  air.     It  has  no 
outlet  to  the  external  ear.     But  there  is  a  passage  or  tube, 
called  the  eustachian  tube,  which  leads  from  the  back  part  of 
the  mouth  to  the  cavity  of  the  internal  ear.     The  air  has  free 
access  from  the  mouth  to  the  inner  ear  through  this  tube. 

The  air  may  be  forced  from  the  mouth  through  this  tube 
into  the  internal  ear,  by  closing  the  lips  and  the  nostrils,  and 
pressing  the  air  from  the  lungs  through  the  windpipe.  The 
air  is  then  felt  pressing  into  the  ear  with  a  sound,  and  some- 
times with  a  loud  sound.  The  acts  of  gaping  and  swallowing 
have  a  somewhat  similar  effect ;  the  latter  creates  a  distinct 
murmuring,  and  the  former  a  sort  of  explosive  sound  in  the 
inner  ear. 

This  tube  holds  the  same  relation  to  the  drum  of  the  ear 
as  the  hole  in  the  side  of  a  martial  drum  does  to  that  musical 
instrument.  When  the  vibration  of  the  air  strikes  upon  the 
membrane  of  the  tympanum,  the  air  within  receives  the  im- 
pression, and  partly  escapes  through  the  eustachian  tube,  and 
thus  the  impression  is  modified. 

915.  There  are  within  the  drum  of  the  ear  three  small  bones, 
which  are  so  arranged  as  to  connect  the  membranous  cover- 
ing with  the  labyrinth,  &c.,  where  the  auditory  nerve  is 
spread,  and  to  convey  the  impressions,  which  are  made  by  the 
undulations  of  the  atmosphere  on  the  outside  of  the  membrane, 
to  the  nervous  filaments  within. 

916.  There  are  also  three  semicircular  canals,  (Fig.  LXIX. 
e,)  and  the  cochlea,  (Fig.  LXIX./*,)  which  have  their  use  in 
the  function  of  hearing,  but  precisely  what  use,  it  is  not  easy 
to  explain.     These  are  placed  within  the  parts  of  the  bone  at 
the  side  and  the  base  of  the  head. 

917.  The  auditory  nerve  passes  from  the  brain  through  a 
hole  at  the  bottom  and  side  of  the  skull,  and  is  spread  about 
in  the  labyrinth  of  the  ear. 

918.  All  the  several  parts  of  the  ear  are  adapted  to  receive 

33* 


390  PHYSIOLOGY   AND   HEALTH. 

the  impressions  made  by  sonorous  bodies,  and  to  convey  tliem 
to  the  brain.  The  sonorous  body  causes  vibrations  in  the  air. 
These  vibrations  strike  upon  the  membrane  of  the  tympanum. 
The  membrane  acts  upon  the  series  of  bones,  and  through 
them  upon  the  internal  parts  and  the  branches  of  the  auditory 
nerve,  and  then  along  this  nerve  the  sonorous  impression  is 
conveyed  to  the  brain,  where  sensation  is  caused,  the  sound  is 
perceived,  and  the  noise  is  heard. 

919.  It  is  necessary,  for  hearing  sound,  that  there  should 
be  a  sonorous  body  to  create  it,  air  to  convey  it,  the  healthy 
ear  to  receive,  and  the  brain  to  perceive  it. 

920.  There  can  be  no  sound  where  there  is  no  air.    If  a  bell 
be  rung  in  an  exhausted  receiver  of  an  air  pump,  no  noise  is 
made.     The  sound  is  more  or  less  loud  according  to  the  state 
of  the  air.     It  is  conveyed  more  distinctly  and  farther  in  the 
direction  of  the  wind  than  in  the  opposite  course,  or  in  any 
direction  when  the  air  is  still.     Thus  we  hear  the  sounds  of 
bells,  &c.,  when  they  are  at  the  windward  better  than  when 
they  are  at  the  leeward  from  us. 

921.  //  is  necessary  that  the  parts  of  the  ear  should  be 
sound  for  perfect  hearing.     When  the  outer  canal  of  the  ear 
is  filled,  or  the  membrane  of  the  tympanum  is  covered,  with 
wax,  hearing  is  impaired. 

922.  The  eustachian  tube  is  sometimes  closed.     Inflam- 
mation of  the  throat,  from  colds,  may  extend  to  the  lining  of 
this  tube,  and  prevent  the  free  passage  of  air.     When  this 
happens  from  this  or  other  causes,  we  feel  an  uneasy  fulness 
and  pressure  within  the  ear,  and  noises  have  an  unnatural  and 
unpleasant  sound. 

When  this  tube  is  closed  from  slight  and  temporary  causes, 
it  can  be  opened  by  gaping,  or  by  pressing  the  air  into  it  from 
the  lungs. 

924.  Hearing  is  impaired,  and  deafness,  in  various  degrees, 
arises,  from  very  many  causes,  and  from  diseases  in  other 
organs  as  well  as  those  within  the  ear.  Worms  in  the  diges- 
tive organs,  scarlet  fever,  measles,  small-pox,  and  influenza 
f»  netimes  produce  this  effect. 


CONCLUSION.  391 

025.  Hearing  requires  the  active  attention  of  the  brain  and 
the  mind ;  and  deafness  or  imperfect  hearing  may  be  caused  by 
the  mere  habit  of  neglecting  impressions  received  by  the  ears. 

926.  The  faculty  of  hearing  may  be  cultivated  to  a  very 
high    degree.      The   practised   hunters   and   the   American 
Indians,  who  are  trained  to  attend  to  and  catch  very  slight 
and  distant  sounds,  can  hear  the  natural  voice  of  animals  and 
men,  or  their   footsteps,  or   even  their  breathing,  or  other, 
noises  indicating  their  existence,  when  others  hear  nothing. 

927.  The  ear  for  music  or  power  of  distinguishing  har- 
monies of  sound,  is  partly  a  natural  gift,  and  partly  a  matter 
of  cultivation.     Almost  all  fe&ve  it  in  some  degree,  and  some 
in  a  very  high  degree.     And  there  are  very  few  in  whom  it 
may  not  be  increased  by  education. 


CONCLUSION. 


Man  responsible  for  Care  of  his  Health.  —  Strength  and  Weakness, 
and  Length  of  Life,  given  according  to  Man's  Faithfulness.  —  In- 
tention of  Nature  that  we  live  happy  and  long.  —  Power  lost  by 
Sickness.  —  Life  shortened.  —  Errors  in  the  Management  of  Health. 
—  Constitution  impaired  in  various  Ways.  —  Effect  of  Education 
and  Circumstances  on  Constitution. 

928.  THE  human  body,  with  its  complicated  structure 
and  organs,  is  left  in  the  charge  of  man.  He  is  appointed  to 
take  it  as  it  comes  from  the  hands  of  the  Creator,  and  de- 
velop and  exercise  it,  direct  its  actions,  supply  its  wants,  and 
govern  all  the  appetites,  according  to  the  requirements  of  life. 
These  conditions  are  exact  and  unyielding,  and  the  good 
or  evil  consequences  are  certain  to  follow  their  fulfilment  or 
neglect.  In  ratio  of  our  obedience  will  be  the  fulness  of  life, 
its  strength,  its  comfort,  and  its  duration.  We  can  have  no 
health  except  so  far  as  we  obey  the  law.  We  can  relax  in 


392  PHYSIOLOGY    AND    HEALTH. 

no  required  exertion,  omit  no  necessary  supply,  and  indulge 
in  no  wrong  appetite  or  propensity.  However  small  the 
error,  the  ever-watchful  sentinel  of  life  visits  it  with  a  propor- 
tionate punishment,  either  of  positive  pain  or  lessened  en- 
joyment. 

929.  Various  powers  are  given  to  us,  and  all  are  necessary 
to  our  being  and  happiness.     The  animal  powers  and  wants, 
the  appetites  and  propensities,  give  pleasure  when  used  and 
gratified  in   suitable   degree.      The  moral   and    intellectual 
powers  give  a  higher  enjoyment.     As  the  mind  needs  the 
body  for  its  earthly  home,  so  the  body  needs  the  mind  as  a 
director.     The  bodily  health  is*  preserved  by  acting  in  obe- 
dience to  the  intellectual  and  moral  faculties,  and  the  mental 
exercise  required  for  this  management  of  the  body  is  neces- 
sary for  the  health  of  the  brain. 

930.  These,  then,  are  the  intentions  of  Nature  —  that  we 
lead  long,  full,  and  happy  lives ;  that,  from  the  beginning  to  the 
end,  we  have  neither  sickness,  nor  weakness,  nor  discontent- 
ment ;  and  that  our  bodies  attain  their  fulness  of  strength, 
and  preserve  it  to  a  good  old  age  ;  that  all  our  faculties  be 
developed  and  strengthened  in  the  performance  of  the  duties 
of  life,  and  every  day  be  filled  with  uninterrupted  faithful- 
ness or  unalloyed  pleasure.     It  is  plain  that  we  fall  short  of 
all  these  blessings  of  life. 

931.  Between  complete  life  and  death   there  is  a  wide 
interval,   in  which  there  are    many  degrees   of  health  and 
strength ;  and  so  accustomed  are  men  to  the  lower  degrees, 
that  they  seldom  look  for  the  higher,  but  seem  generally  con- 
tent with  less.     But  there  is  a  point  in  which  there  is  a  ful- 
ness of  physical,  intellectual,  and  moral  power.     This,  and 
.his  alone,  is  perfect  health. 

932.  It  is  rare  that  any  one  passes  any  considerable  period 
without  some  sickness  so  severe  as  to  compel  him  to  suspend 
his   usual  employment,  and  give   himselF.up  entirely  to  the 
work  of  recovery.     Sickness  and  weakness,  in  one  form  or 
other,  seem  to  be  expected  as  the  occasional  lot  of  all ;  and 
much  of  our   time,    power,    and   comfort,    is    thereby    lost 


CONCLUSION.  393 

But  the  whole  amount  of  these  which  we  lose  by  sickness 
that  prostrates  us,  is  much  less  than  the  amount  of  those  lost 
by  the  many  lesser  ailments  or  debilities  which  impair  our 
energies  and  diminish  our  ease  in  small  degrees,  and  for 
short  periods,  and  thus  lay  light,  but  very  frequent  taxes 
upon  our  vitality.  There  are  hours  or  days  when  we  have 
colds,  headache,  pain  or  stiffness  in  the  limbs ;  when  we  are 
heavy  and  inert  from  indigestible  or  over-abundant  food,  or 
other  causes;  when  we  are  timid  or  irresolute,  irritable,  peev- 
ish, or  melancholy ;  when  we  have  not  the  full  control  of  all 
our  faculties,  because  the  body  or  the  mind  does  not  willing- 
ly, or  cannot,  direct  all  its  energies  to  our  intended  purpose 
These,  individually,  make  but  slight  deductions  from  the 
force,  the  productiveness,  and  the  enjoyments  of  life;  yet, 
when  added  together,  their  sum  is  very  great. 

933.    Not  only  are  the  power  and  the  value  of  life  very 
materially  diminished  in  its  course  by  the  greater,  and  lesser 
sicknesses  and  indispositions,  weakness,  and  languor,  but  life 
itself  is  shortened  by  these  and  other  causes  connected  with 
our  existence.     The  natural  period  of  human  life,  in  favora- 
ble circumstances,  is  supposed  to  be  seventy  years;  yet  com- 
paratively few  reach  that  term.     The  average  duration  of 
life  differs  in  different  countries.     According  to  the  bills  of 
mortality,  the  average  age  of  those  wjio  died  in  England  was 
30  years  and  10  months ;  in  Sweden,  30  years  and  8  months ; 
and  in  Russia,  of  the  males,  22  years.     In  Massachusetts 
12-2,  in  England  13'8,  in  Ireland  10'6,  in  Sweden  14'6, 
arid  in  France  18'9  per  cent,  of  all  who  died  were  over  70 
years  old.    There  is  still  a  wider  difference'm  the  duration  of 
life  in  the  various  classes  of  society  even  in  the  same  place. 
In  England,  the  average  duration  of  life  of  the  families,  in- 
cluding the  parents  and  children,  among  the  most  favored 
classes,  was,  in  Liverpool,  35;  in  Rutlandshire,  52;  and  in 
Wiltshire,  60  years ;  and  among  the  poorer  classes  it  was, 
in  Liverpool,   15  ;  in  Rutlandshire,  38 ;    and  in  Wiltshire, 
33  years.     Wherever  the  same  examination  has  been  made 
in  this  country,  a  similar  difference  in  the  duration  of  life 
has  been  shown. 


394  PHYSIOLOGY    AND   HEALTH. 

934.  Thus  we  see  that  the  most  favored  people  fall  short 
of  the  full  period  of  their  earthly  existence,  and  the  poor  in 
some  places  dooiot  average  one  fourth  of  it.     If  we  add  to 
this  abbreviation  of  life  the  deductions  made  by  the  lighter 
and  temporary  indispositions,  and  the  severer  and  protracted 
sicknesses,  and  deduct  the  whole  from  the  allotted  period  of 
threescore  and  ten  years,  it  is  manifest  that  a  large  part  of 
mankind  receive  but  a  small  share  of  the  amount  of  active 
and  productive  life  that  seems  intended  for  them. 

935.  This  great  abridgement  of  life  is  not  caused  by  im- 
perfection of  the  Creator's  work.     There  is  nothing  in  the 
healthy  organization  that  indicates  the  necessity  of  disease, 
debility,  or  early  death.     Nature  has  not  made  the  mistake 
of  giving  man  a  set  of  organs,  all  of  which  may  continue  in 
successful  operation  seventy  years,  with  the  exception  of  the 
lungs,  or  stomach,  or  brain,  which  will  wear  out,  or  become 
disordered  and  fail,  in  half  that  time.,    These  are  not  the 
mistakes  of  nature  ;  for,  with  the  exception  of  hereditary  dis- 
eases and  imperfections  which  some  parent  has  engrafted  on 
his  own  constitution  and  transmitted  to  his  children,  most 
men    are   born  with   perfect   and  equal   organization,  with 
equal  power  of  action    and   endurance  in  all  the   parts  of 
their  frames. 

936.  Few  die,  at  the  end  of  their  full  period,  from  ex- 
haustion of  all  their  physical  powers  by  proper  and  regular 
action  through  the  whole  period.    Most  persons  die,  before 
the  natural  term  is  completed,  from  the  failure  or  disease  of 
some  of  the  organs  rather  than  from  general  decay  in  old 
age.    In  every  1600  who  died  in  Massachusetts  during  the 
22  years  preceding  1864,  314  died  of  diseases  of  the  lungs, 
137  of  diseases  of  the  digestive  organs,  78  of  diseases  of 
the  brain,  and  only  54  of  old  age. 

937.  Here  is  a  very  small  portion  —  but  little  more  than 
one  twentieth  —  that  died  because  the  machinery  of  life 
was  worn  out.     The  great  majority  died  from  the  disease 
or  failure  of  some  one  of  the  organs  to  sustain  itself  and 
perform  its  part  in  the  work  of  life,     if  these  organs  had 


CONCLUSION.  395 

originally  equal  power,  and  were  prepared  to  perform  equal 
work,  there  must  have  been  some  variation  from,  or  failure 
in,  the  conditions  of  being.  This  failure  of  any  one  or  all 
of  the  organs  may  arise  from  one  of  two  causes  —  from 
some  deficiency  of  the  building  up  the  body,  in  the  devel- 
opment and  strengthening  of  its  organs,  or  from  some  mis- 
take in  the  expenditure  of  its  powers. 

938.  Strength  should  be  constantly  added,  by  means  of 
food,  air,  exercise,  &c.,  and  a  portion  of  this  strength  may 
be  expended  through  the  muscles,  or  the  brain  and  nervous 
system.     We  may  err  in  the  building  up  the  body,  by  sup- 
plying it  with  insufficient,  innutritious,  indigestible,  or  exces- 
sive food,  or  with  impure  air.     Or  we  may  repair  the  vital 
machine  with  too  much  cost  of  nervous  power,  or  with  the 
wear  and  the  waste  of  the  organs  of  supply.     To  this  daily 
repair  of  the  body  some  strength  must  be  given.     This  re- 
pair must  be  attended  to  before  any  other  matters;  and,  if  it 
be  faithfully  made,  it  will  generate  more  strength  than  it 
consumes,  and   leave  a  surplus  portion  to  be  devoted   to 
other  purposes. 

939.  The  energy,  or  power  of  the  body  for  its  self-suste- 
nance, and  for  its  action  beyond  itself,  is  what  is  called  the 
constitution.      This  vital  constitution,  in   regard   to  health 
and  action,  may  be  likened  to  capital  in  trade,  and  the  sur- 
plus  power   of  action   may  be   considered    as   its   income. 
That  amount  of  income,  or  surplus  strength,  which  is  gath- 
ered daily,  and  no  more,  may  be  daily  expended.     But  if 
the  expenditure  exceeds  the  income,  and  more  strength  is 
expended  than  is  gained,  it  draws  so  much  upon  the  capital, 
or  the  constitution,  and  then  the  body  must  lie  still  and  rest, 
to  regain  its  loss. 

940.  There  are  manifold  ways  in  which  the  gathered 
power    may  be   expended, —  in  mental  labor,  or  muscular 
exercise,  in  grief,  irregularities  and  intemperance  of  every 
sort,  excessive  action  of  the  digestive  organs,  stimulation 
of  alcohol,  excitement,  passion,  exposure  to  cold,  &c.     In 
most  of  these   ways,  a  limited   amount  of  power  may  be 


396  PHYSIOLOGY    AND    HEALTH. 

expended,  and  leave  the  capital  unimpaired ;  but  any  excess, 
however  small,  like  an  excess  of  expenditure  of  money  over 
the  income,  must  be  taken  out  of  the  constitution.  All 
failure  in  the  building  up,  all  privations  of  nutriment,  of 
sleep,  or  of  due  exercise,  or  bathing,  however  small,  in- 
asmuch as  the  body  is  thereby  strengthened  less,  produce 
so  much  less  income,  and  create  a  deficiency  of  the  vital 
power. 

941.  The  excess  of  expenditure  of  strength,  in  every  way, 
over  the  daily  income,  and   all  deficiency  in  strengthening, 
then,  wear  upon  the  constitution.     In  these  many  ways,  the 
deterioration  may  be  very   slight  and  imperceptible  at  the 
time  ;  the  evil   consequences  may  not    be  great  enough  to 
call  our  attention  to  them ;  yet  the  power  of  life  is  dimin- 
ished, there  is  less  energy  in  the  action  of  the  organs,  and 
less  power  to  resist  causes  of  disturbance.      Each  one  of 
these  errors  diminishes  the  capital  of  life  in  proportion  to  its 
extent.     One  takes  a  li'ttle,  and  another  a  little,  and  yet  the 
loss  is  unnoticed  until  the  whole,  added  together,   weakens 
the  constitution,  impairs  the  health,  and  wastes  the  strength 
so  much,  that  some  other  cause  creates  a  perceptible  dis- 
order or  pain,  and  this  we  call  disease.     This  may  be  fatal, 
not  because  of  its  own  force  or  violence,  but  because  the 
vital   force  had  been  previously  so  much  reduced,  that    it 
could  not  resist  this  cause  of  disturbance.     Thus  the  system 
is  not  only  laid  open  to  attacks  of  disease,  but  its  power  of 
overcoming  it  is  lost ;  as  men's  affairs  are  sometimes  embar- 
rassed apparently  by  a  new  debt  or  loss,  but  really  because 
their  capital  had  been  diminished  so  much  by  previous  mis- 
fortune or  mismanagement,  that  the  new  obligation   is  an 
insupportable  burden. 

942.  The  natural  and  artificial  varieties  of  human  con- 
stitution are    variously    affected   by  education,    habits,    cir- 
cumstances, employments,  and  localities.     These  influences 
may  be  so  used  as  to  diminish,  and  often  remove,  these  in- 
equalities, or,  on  the  contrary,  to  increase  and  establish  them. 
ff  they  are  carefully  regarded   in  the  training  of  children 


CONCLUSION.  397 

and  youth,  in  the  selection  of  occupations  or  places  of  resi- 
dence, the  weak  may  become  strong,  or  a  part  or  organ  that 
cannot  be  strengthened  will  not  be  compelled  to  bear  * 
burden  beyond  its  powers.  But,  owing  to  neglect  of  this 
principle,  the  circumstances  of  life  are  often  so  used  that  the 
weak  organs  become  weaker ;  the  inequality  is  thereby  in- 
creased, and  the  health  is  impaired.  The  robust  and  the 
feeble,  the  nervously-excitable  and  the  lymphatic,  obviously 
need  different  employments.  Those  who  have  weak  lungs, 
and  inherit  predisposition  to  consumption  or  asthma,  cannot 
safely  engage  in  the  same  pursuits,  or  inhabit  the  same 
localities,  which  would  be  beneficial  to  one  of  more  perfect 
organization.  Thackrah,  in  his  valuable  work  on  the  Influ- 
ence of  Employments  on  Health  and  Longevity,  says  that 
not  fifty  of  the  fifty  thousand  who  annually  die  of  consump- 
tion in  Great  Britain,  would  fall  by  this  disease,  if  proper 
occupation  and  habits  were  adopted.  The  dyspeptic  needs 
in  active,  and  not  a  sedentary  avocation;  and  the  nervous 
suffer  if  the  brain  is  called  into  excessive  exercise  by  study, 
or  the  anxious  cares  of  business ;  and  those  who  are  subject 
to  catarrh  and  asthma  are  made  worse  by  working  in  the 
dusty  trades  or  places. 

943.  Out  of  our  own  organization,  and  with  the  external 
means  offered  to  us  by  a  generous  Providence,  we  are  to 
sustain  our  health  and  prolong  our  life.  For  this  purpose, 
as  a  judicious  engineer  first  learns  the  structure,  and  uses, 
and  power  of  his  machine,  and  then  supplies  all  its  materials, 
adapts  the  surrounding  circumstances  to  its  wants,  and  gov- 
erns its  movements,  and  applies  its  powers  precisely  to  its 
intended  purposes,  so,  in  the  management  of  our  vital  ma- 
chine, we  must  first  learn  its  structure,  powers,  and  wants, 
and  then  supply  the  one  and  direct  the  other  precisely 
according  to  the  law  of  life.  This  responsibility  for  the 
care  of  the  body  and  the  mind  comes  upon  every  one,  in 
every  condition ;  and  whosoever  discharges  it  with  intelli- 
gence and  faithfulness,  will  increase  his  powers  and  his 
enjoyments  and  have  length  of  days  on  earth. 
34 


QUESTIONS 

ON 

JAEVIS'S  PRACTICAL  PHYSIOLOGY. 

PREPARED  BY 

EV.  SOLOMON  ADAMS, 

Of   BOSTON,    MASSACHUSETTS. 

PART    I. 

DIGESTION  AND  FOOD. 

CHAPTER  I. 

1.  What  changes  take  place  in  the  animal  body  from  birth  to  man- 
hood ? 

2.  What  law  is  impressed  on  all  animal  beings? 

3.  What  makes  food  necessary? 

4.  What  is  the  difference  between  food  and  living  flesh  ? 

5.  What  is  the  process  of  this  change? 

6.  What  organs  constitute  the  digestive  apparatus? 

7.  What  offices  do  the  several  parts  of  the  mouth  perform  in  the 
digestive  process  ? 

8.  What  teeth  have  carnivorous  animals? 

9.  What  teeth  have  herbivorous  animals  ? 

10.  To  what  kinds  of  food  are  the  teeth  of  man  adapted? 

11.  How  many  teeth,  and  what  kinds,  has  man  ? 

12.  How  are  the  teeth  set  in  the  jaw  ?    Of  what  are  they  composed  ! 
What  causes  their  decay  ? 

13.  How  may  the  cause  of  decay  be  prevented  ? 

14.  Why  are  decayed  teeth  painful  ? 

CHAPTER  II. 

15.  When  do  the  glands  of  the  mouth  secrete  saliva  ? 

16.  When  do  the  glands  refuse  to  perform  this  office  ? 

17.  What  must  be  done  to  food  before  it  is  swallowed? 

18.  Describe  the  second  chamber  of  the  mouth. 

(399) 


400  QUESTIONS    ON 

19.  How  many  passages  open  from  this  chambo/?     What  are  they  I 

20.  Where  is  the  mouth  of  the  windpipe?     What  is  the  epiglottis? 

21.  What  are  the  offices  of  the  epiglottis? 

22.  Why  can  we  not  breathe  when  swallowing? 

23.  Describe  the  oesophagus  or  gullet. 

24.  How  does  the  (Esophagus  move  the  food  towards  the  stomach? 


CHAPTER  III. 

25.  Describe  the  stomach?     Why  is  it  always  full  ? 

26.  On  what  does  the  average  size  of  the  stomach  depend? 

27.  What  is  the  texture  of  the  stomach  ?     Of  how  many  coats  is  it 
composed?     Describe  the  outer  or  peritoneal  coat. 

28.  Describe  the  middle  or  muscular  coat. 

29.  The  inner  or  mucous  coat. 

30.  What  familiar  illustration  of  these  coats? 

31.  What  office  do   these  coats  severally  perform   in  the  digestive 
process?     By  what  is  the  food  dissolved  in  the  stomach  ? 

32.  33.  "What  effect  has  the  gastric  juice  on  all  proper  kinds  of  food  ? 

34.  What  opportunity  had  Dr.  Beaumont  ? 

35,  36.  What  observations  of  Dr.  Beaumont  and  others  have  made 
known  the  steps  of  the  process  ? 

CHAPTER  IV. 

37.  Do  Dr.  Beaumont's  observations   explain  the  process?  or  only 
reveal  the  several  stages  of  digestion  ?     What  advantage  results  from 
a  complete  mastication  ? 

38.  In  what  quantity  is  the  gastric  juice  secreted  ? 

39.  What  is  the  limit  of  this  secretion  ?     What  is  the  consequence 
of  this  limit? 

40.  Have  we  any  measure  of  the  amount  of  food  which  we  ought 
to  take  at  a  meal  ?     How  can  this  measure  be  ascertained  ? 

41.  What  condition   is   necessary  to  make  this  measure  a  guide  ? 

42.  What  is  hunger?     When  felt? 
43,44.  Give  the  illustration. 

45.  When  does  the  work  of  digestion  begin?     How  long  is  the  gas- 
tric juice  secreted  ? 

CHAPTER  V. 

46.  What  is  the   relative  position  of  the   stomach,  lungs,  and  dia- 
phragm ? 

47.  How  does  respiration  keep  the  stomach  in  motion  ?    What  effect 
has  this  motion  on  digestion? 

48.  To  what  substance  is  all  the  food  reduced  in  the  stomach  ! 

49.  What  temperature  does  digestion  require  ? 

50.  Relate  Dr.  Beaumont's  experiments. 


JARVIS'S    PRACTICAL    PHYSIOLOGY.  401 

51.  What  inferences  may  be  drawn  from  these  observations  on  the 
temperature  of  the  stomach  ? 

52.  What  part  of  the  stomach  first  receives  the  food  ftom  the  mouth? 
What  is  the  pyloric  valve  ?      What  is  its  office  ? 

53.  What  power  of  discrimination  does  it  seem  to  possess? 

54.  How  does  it  treat  improper  food  ?     What  is  our  sensation  at  such 
tf  mes  ? 

55.  How  does  this  struggle   between  the  stomach  and  the  pylorus 
end?     What  are  the  effects? 

CHAPTER  VI. 

56.  Are  all  articles  of  food  digested  with  equal  ease  ? 

57.  What  is  the  average  time  which  a  healthy  stomach  requires  for 
digestion  ? 

58.  Give  the  results  of  observations  on  St.  Martin,  in  relation  to  the 
time  of  the  digestive  process? 

CHAPTER  VII. 

59.  What  is  the  first  work  of  the  stomach  in  digestion? 

60.  What  is  the  effect  of  drink  taken  with  food?     What  suggestion 
is  offered  to  persons  who  have  weak  stomachs? 

61.  What  is  the  proper  moisture  for  food? 

62.  Will  the  stomach  act  more  easily  on  a  large  or  on  a  small  quan- 
tity of  food?     Is  the  quantity  of  nutriment  always  in  proportion  to  the 
bulk  of  food  ? 

63.  With  what  should  concentrated  food  be  mixed  ?      What  is  the 
practice  of  some  rude  northern  tribes  ? 

64.  Is  the  nature  of  the  food  a  matter  of  much  importance  ?     . 

65.  66,  67.  Give  the  illustrations. 

CHAPTER  VIII. 

68.  What  is  chyme?     When  does  the  food  become  chyme?     Into 
what  organ  does  the  chyrne  pass  from  the  stomach  ? 

69.  What  coats  compose  the  alimentary  canal? 

70.  How  does  the  mucous  membrane  of  the  alimentary  canal  differ 
from  that  of  the  stomach  ?     What  are  its  structure  and  offices  ? 

71.  What  is  the  office  of  the  pancreas? 

72.  What  duty  is  performed  by  the  digestive  juices  ? 

73.  What  are  the  lacteal  absorbents  ?     What  the  lacteal  duct  ? 

74.  What  are  the  absorbent  veins  ? 

75.  How  is  the  digested  food  disposed  of? 

76.  On  what  does  the  proportion  of  chyle  depend  ?     What  are  the 
remote  effects  of  imperfect  mastication  ? 

77.  Into  what  stages  is  the  process  of  digestion  divided?     How 
should  each  stage  be  performed  ? 

34* 


402  QUESTIONS    ON 

CHAPTER  IX. 

78.  How  much  do  we  know  of  the  digestive  process? 

79.  How  far  does  the  agency  of  man  go  in  this  process  ? 

80.  When  are  we  unconscious  of  the  pro  cess  in  the  stomach  ?  When 
do  we  become  conscious  of  it  ? 

81.  What  sensations  accompany  healthy  digestion? 

82.  At  what  stage  of  digestion  does  man's  agency  cease,  and  when 
does  nature  take  care  of  it  ?     What  guide  is  needed  ? 

83.  What  is  hunger  ? 

84.  What  incorrect  suppositions  are  mentioned  1    Does  hunger  return 
as  soon  as  the  stomach  is  empty  1 

85.  What  creates  a  desire  for  food  1     What  forms  of  disease  prove 
this? 

86.  Where  is  the  sensation  of  appetite  1     What  may  result  from  a 
diseased  state  of  the  nerves  of  the  stomach  1 

87.  Can  we  need  food  without  being  conscious  of  it? 

88.  89.  Give  the  illustrations. 

CHAPTER  X.  ' 

90.  How  is  the  appetite  affected  by  various  bodily  and  mental  states  ? 

91.  What  does  hunger  indicate  1    How  do  the  wants  of  the  body  vary 
in  a  healthy  state  of  the  system  1 

92.  Of  what  is  appetite  the  usual  sign?     Should  we  eat  when  we 
are  not  hungry  1 

93.  When  does  the  desire  for  food  fail  to  give  evidence  of  digestive 
power  ? 

94.  What  distinction  exists  between  appetite  and  taste  ? 

95.  96,  97.  Relate  some  remarkable  instances  of  absence  of  appe- 
tite under  disease,  or  excitement. 

CHAPTER  XI. 

98,  99.  Relate  some  instances  of  extraordinary  appetite  for  food  ? 
100,  101.  What  causes  may  produce  this  extraordinary  appetite? 

102.  When  is  a  new  supply  of  nutriment  needed? 

103.  On  what  does  the  interval  between  the  hours  of  eating  depend  ? 

104.  How  may  the  appetite  be  trained  to  return  at  regular  intervals  1 

105.  106.  Give  some  illustrations  of  the  accommodating  power  of  the 
stomach  ? 

107.  Will  the  stomach  bear  sudden  changes  in  the  time  of  eating? 

108.  Give  an  illustration. 

109.  What  are  the  effects  of  irregular  hours  of  eating  ? 

110.  What,  in  general,  are  proper  intervals  of  eating  ? 

CHAPTER  XII. 

111.  Why  may  the  interval  between  the  evening  and  morning  meals 
be  longer  than  others  ?     Why  breakfast  soon  after  rising  ? 

112.  What  is  recommended  when  the  morning  meal  is  late? 

113.  When  does  the  body  sustain  labor  and  exposure  best? 

114.  What  advice  is  given  in  section  114? 


JARVIS'S    PRACTICAL    PYHSIOLOGY.  403 

115.  Who  especially  should  take  early  morning  refreshment? 

116.  What  usages  have  prevailed  in  regard  to  the  time  of  eating 
dinner? 

117.  What  faulty  custom  is  mentioned?     The  common  remedy? 

118.  Illustrate. 

119.  Who  may  properly  take  a  forenoon  lunch  ? 

120.  How  many  daily  meals  are  needed  ?     When  may  supper  be 
omitted  ? 

121.  How  long  before  sleeping  should  supper  be  eaten  ?     Why? 

122.  What  custom  meets  the  wants  of  the  body?     What  are  the 
effects  of  more  frequent  meals  ? 

CHAPTER  XIII. 

123.  Can  the  quantity  of  food  be  fixed  by  a  uniform  rule?     . 

124.  What  is  the  rule  in  the  British  navy?     In  the  army  of  tho 
United  States?      What  the  rule  for  emigrant  passengers? 

125.  On  what  does  the  proper  quantity  depend  ?     Do  corpulency 
and  leanness  depend  on  the  quantity  of  food  ? 

126.  What  illustration  is  given? 

127.  How  does  occupation  affect  the  quantity  of  food? 

128.  What  variation  in  diet  should  the  same  individual  malte  ? 

129.  What  change  of  diet  does  change  of  occupation  require  ? 

130.  What  are  the  consequences  of  neglecting  this  change  in  the 
quantity  of  food  ? 

131.  State  facts  which  have  occurred  at  Cambridge. 

132.  Why  do  growing  persons  require  more  food  than  adults?    Why 
convalescents  more  than  the  healthy? 

CHAPTER  XIV. 

133.  What  has  been  shown  in  sections  93,  94. 

134.  How  long  may  we  safely  eat? 

135.  Why  should  we  eat  slowly,  and  masticate  thoroughly? 

136.  What  would  be  a  monitor  of  health,  and  preventive  of  disease 
connected  with  eating? 

137.  Who  will  not  err  in  his  diet? 

138.  What  sensations  come  from  eating  enough  ?     What  from  eat- 
ing too  much  ? 

139.  Do  evil  consequences  always  follow  excess  of  eating? 

140.  Why  is  it  not  economy  of  time  to  eat  hastily  ? 

141.  Illustrate. 

142.  What  habits  often  prevail  in  hotels  and  steamboats  ? 

CHAPTER  XV. 

143.  What,  is  one  proof  of  Divine  benevolence  and  wisdom  ?     What 
two  principles  are  to  be  observed  ? 

144.  What  abuse  may  come  from  the  pleasure  of  eating? 
144,  145.  Illustrate,  and  specify  a  difference. 

146.  What  is  a  cornmoji  error  in  regard  to  eating  ? 

147.  What  properties  of  food  do  most  persons  know  ?     Of  what  are 
they  ignorant  ? 


404  QUESTIONS    ON 

148.  What  usages  of  the  table  are  injurious? 

149.  What  rites  of  hospitality  violate  the  laws  of  digestion  ? 

150.  How  are  children  often  improperly  indulged? 

151.  Is  such  indulgence  confined  to  children? 

152.  What  are  the  consequences  of  these  indulgences  of  appetite? 

153.  What  are  the  effects  of  deficient  or  bad  food? 

154.  Give  illustration. 

CHAPTER  XVI. 

155.  What  happens  when  some  one  organ,  or  portion  of  the  body  is 
in  action  ? 

156.  Why  should  other  organs  rest  while  the  digestive  organs  are 
active? 

157.  What  comes  from  attempting  the  vigorous  action  of  two  parts 
of  the  body  at  the  same  time  ? 

158.  What  kind  of  mental  action  interferes  with  digestion?     What 
kind  does  not? 

159.  Relate  experiments  on  hounds. 

160.  What  kind  of  exercise  is  compatible  with  the  digestive  process  ? 

161.  What  is  the  effect  of  exercising  any  of  the  organs  violently? 

162.  What  is  the  effect  on  mental  action? 

163.  What  is  fatigue?     What  is  the  process  of  rest? 

164.  Why  is  a  short  internal  of  repose  needed  between  hard  labor 
and  eating  ? 

165.  State  illustrations. 

CHAPTER  XVII. 

166.  What  conditions  are  recommended  during  the  time  of-  eating? 

167.  What  should  be  avoided  during  the  eating  hour  ? 

168.  What  is  lost  by  disregarding  the  laws  of  digestion? 

169.  How  is  dyspepsia  produced? 

CHAPTER  XVIII. 

170.  In  determining  what  kind  of  food  should  be  eaten,  what  pre- 
liminary questions  are  important? 

171.  What  question  is  still  discussed? 

172.  What  examples  do  both  parties  find? 

173.  Are  there  any  advocates  for  an  exclusively  flesh  diet? 

174.  What  is  the  general  belief  in  regard  to  diet?     Why? 

175.  How  do  different  kinds  of  food  differ  in  their  effect  on  the  body  ? 

176.  What  influence  has  climate  on  digestion?     What  is  the  food 
in  the  polar  regions  ? 

177.  What  in  tropical  ?     What  usually  in  temperate  regions  ? 

CHAPTER  XIX. 

178.  What  differences  in  the  temperaments  of  men  ? 

179.  What  are  marks  01"  a  lymphatic  temperament?     What  food 
suits  it? 


JARVIS'S   PRACTICAL   PHYSIOLOGY.  405 

180.  How  is  the  nervous  temperament  distinguished?  What  food 
suits  it?     What  does  not? 

181.  What  accompanies  the  sanguine  temperament?     What  food  is 
injurious  ? 

182.  How  is  the  bilious  temperament  distinguished  ? 

183.  What  examples?     What  food  is  proper  for  it? 

184.  What  may  we  observe  among  our  associates  ? 

185.  What  is  the  consequence  of  disregarding  temperament  in  the 
legulation  of  diet? 

CHAPTER  XX. 

186.  How  does  childhood  differ  from  old  age? 

187.  What  modification  of  diet  does  this  difference  require  ? 

188.  How  should  the  habits  of  an  individual  modify  diet? 

189.  What  relation  has  diet  to  employment? 

190.  What  is  the  consequence  of  neglecting  this  law  ? 

191.  What  does  a  change  from  light  to  severe  labor  require? 

CHAPTER  XXI. 

192.  In  all  kinds  of  food  what  two  things  are  to  be  considered  ?    Are 
they  identical? 

193.  Who  especially  should  make  this  distinction?     Why? 

194.  What  are  the  natural  effects  of  stimulation?     Illustrate. 

195.  Why  are  condiments  and  stimulants  injurious  to  a  healthy  sto«. 
mach  ? 

196.  What  is  the  effect  of  alcohol? 

197.  How  do  all  stimulants  affect  the  natural  sensibility  of  the  tongue 
and  mouth  ? 

198.  Can  the  original  sensibility  be  recovered?     What  has  Dr.  Kit- 
chenor  remarked  ? 

199.  What  do  we  learn  from  this  examination? 

200.  What  must  every  individual  do  ? 

201.  Why  cannot  a  dietetic  code  be  framed  suited  to  all  men? 


PART  II. 

CIRCULATION  OF  THE  BLOOD  AND  NUTRITION. 
CHAPTER  I. 

202.  What  becomes  of 'the  chyle? 

203.  What  is  the  apparatus  of  the  circulation  of  the  blood  ? 
304.  Describe  the  heart. 


406  QUESTIONS    ON 

205.  How  is  the  heart  situated  ?     What  is  its  beating  ? 

206.  How  is  the  heart  divided  ? 

207.  What  are  the  other  divisions  of  the  heart? 

208.  What  are  the  valves  ?     How  do  they  act? 

209.  What  are  the  sets  of  blood  vessels  ?    "What  relations  have  they 
to  the  heart?     The  body  ? 

210.  Describe  the  arteries. 

211.  What  is  the  aorta?     What  its  divisions? 

212.  Describe  the  subclavian  arteries. 

213.  Describe  the  arteries  of  the  neck,  head,  and  face. 

214.  What  are  the  inguinal  arteries?  the  femoral?     How  are  the 
arteries  finally  distributed  ? 


CHAPTER  II. 

215.  What  are  the  veins? 

216.  What  is  the  vena  eava?     What  are  its  offices? 

217.  What  are  the  large  branches  of  the  veins? 

218.  How  are  the  veins  finally  distributed  ? 

219.  How  are  the  arteries  or  veins  arranged  in  respect  to  each  other  1 

220.  What  is  the  capillary  system? 

221.  What  is  the  general  circulation? 

.     222.  Where  are  the  arteries  situated?     Why?     When  is  pulsation 
felt? 

223.  Where  are  the  veins  situated  ?     Why  ? 

224.  How  does  the  blood   pass  from  the  left  to  the  right  side  of  the 
heart?     How  from  the  right  to  the  left? 

225.  Describe  the  pulmonary  arteries.     The  pulmonary  veins. 

226.  Describe  the  double  circulation. 


CHAPTER  III. 

227.  By  what  force  is  the  blood  conveyed  through  the  arteries  ? 

228.  How  and  upon  what  does  the  heart  act? 

229.  What  prevents  the  blood  from  flowing  backwards? 

230.  How  are  the  arteries  distributed?     What  produces  their  beat- 
ing? 

231.  How  is  blood  moved  through  the  arteries? 

232.  How  much  blood  in  a  man  of  average  size?     In  what  time 
does  it  all  circulate  through  the  system? 

233.  What  circumstances  affect  the  rate  of  circulation? 

234.  Whose  pulsations  are  strong?     Whose  feeble?     Why? 

235.  How  do  mental  states  affect  the  circulation? 

236.  Is  the  expansion  of  the  arteries  the  same  in  all  parts  of  the 
body? 

237.  How  may  we  arleet  the  circulation  ? 


JARVIS'S   PRACTICAL   PHYSIOLOGY.  407 

CHAPTER  IV. 

238    What  materials  of  the  body  are  obtained  from  the  blood? 

239.  What  elementary  substances  are  found  in  the  blood  ? 

240.  Are  all  these  elements  found  in  every  texture  of  the  body  ? 

241.  At  what  stage  is  the  blood  changed  to  flesh? 

242.  Which  makes  the   largest  demand  on  the  blood,  growth  or 
change  of  particles? 

243.  How  are  the  new  atoms  of  flesh  disposed  of? 

244.  What  is  the  office  of  absorbents  ? 

245.  Give  Dr.  Johnson's  description. 

CHAPTER  V. 

246.  Do  the  particles  that  compose  our  bodies  remain  the  same  ? 

247.  How  can  the  atoms  change,  without  a  change  of  the  body? 
Illustrate. 

248.  What  experiments  have  been  tried  on  pigs?     What  result? 

249.  How  is  this  fact  explained? 

250.  During  what  part  of  life  is  the  work  of  the  arteries  and  absor- 
bents equal  ? 

251.  When  does  nutrition  predominate?     When  absorption  ? 

252.  What  is  the  effect  of  all  exercise  on  nutrition  and  absorption? 

253.  What  law  is  a  physical  one,  as  well  as  moral  ? 

254.  How  may  the  relative  activity  of  destruction  and  creation  be 
disturbed  ? 

255.  How  are  wens  and  other  fleshy  tumours  produced  ?    How  scat- 
tered ? 

CHAPTER  VI. 

256.  Is  the  work  of  nutrition  and  absorption  equally  rapid  at  all  pe- 
riods ? 

257.  Whose  flesh  is  ever  young  ?     Whose  ever  old  $ 

258.  Where  does  our  knowledge  of  nutrition  end? 

259.  What  elements  do  the  nutritive  organs  select  to  form  fat?  hair  T 
muscle  ? 

260.  Do  the  nutritive  organs  ever  misplace  a  particle  ? 

261.  How  does  arterial  blood  differ  from  venous? 

262.  By  what  means  is  the  venous  blood  renovated  ? 


PAKT    III. 
RESPIRATION. 

CHAPTER  I. 

263.  How  are  the  wasted  particles  of  the  body  d.ispo-ed  of? 

264.  Of  what  parts  does  the  venous  blood  consist?     Why  would  not 
these  nourish  the  body  ?     To  what  process  must  they  be  submitted  1 


408  QUESTIONS   ON 

265,  266.  How  are  the  lungs  situated  and  protected? 
267.  Describe  the  spine.    268.  Breast- bone.    269.  Ribs.    270.  Their 
position. 

CHAPTER  II. 

271.  What  provision  for  moving  the  ribs  ? 

272.  What  motion  of  the  ribs  expands  the  chest? 

273.  274.   What  is  the  diaphragm,  and  its  office  in  respiration  ? 
275.  Describe  the  process  of  inspiration.     276.  Of  expiration. 

277.  Explain  fig.  VI. 

CHAPTER  III. 

278.  What  is  the  relative  position  of  the  heart  and  lungs?     What 
the  substance  of  the  lungs  1 

279.  Describe  the  air-tubes;  the  blood-vessels  of  the  lungs'? 

280.  What  is  the  windpipe  ? 

281.  What  is  the  organ  of  voice  ?     Its  diseases? 

282.  How  is  the  windpipe  divided?     What  are  the  air-cell^? 

283.  How  are  the  air-vessels  lined  ?     What  is  coughing  ? 
'284.  How  may  sensibility  be  impaired? 

285.  How  are  the  rnirrute  arteries  separated  from  the  air-cells? 

286,  287.   What  two  operations  constitute  respiration? 
288.  Name  the  organs  employed  in  respiration. 


CHAPTER  IV 

289.  What  elements  of  waste  matter  are  separated  from  the  blood? 
How  ? 

290.  Into  what  does  carbon  enter  and  compose  a  part? 

291.  What  are  the  constituents  of  the  atmosphere? 

292.  What  is  oxygen,  and  what  are  its  combinations? 

293.  What  is  nitrogen  and  some  of  its  combinations? 

294.  What  new  compounds  are  formed  in  the  lungs? 

295.  What  is  carbonic  acid  ?     Where  found  ?     Its  properties  ? 

296.  297.  What  interchange  takes  place  between  the  air  and  blood  ? 


CHAPTER  V. 

298.  In  what  state  does  the  blood  enter  the  lungs?     In  what  state 
does  it  leave  them  ? 

299.  Why  do  the  veins,  and  the  flushed  cheek  differ  in  color? 

300.  What  is  the   effect  of  respiring  the  same   air  several  times? 
•Haw  much  does  our  respiration  change  it? 

301.  Give  Davy's  experiment. 

302.  What  is  the  point  of  saturation  ? 

303.  How  may  it  be  shown  that  water  comes  from  the  lungs? 

304.  What  other  matters  are  carried  off  by  the  lungs  f 


PHYSIOLOGY.  409 


CHAPTER  VI. 

305.  What  part  of  the  oxygen  of  the  air  does  one  respiration  con- 
sume ? 

306.  Will  a  second  respiration,  and  a  third,  consume  each  another 
fourth  ? 

307.  Give  an  illustration. 

308.  Will  any  other  proportion  of  oxygen,  than  that  which  is  in  pure 
air  answer  ? 

309.  What  besides  the  loss  of  oxygen  unfits  the  air  for  a  second  res- 
piration? 

310.  What  is  the  limit  of  the  capacity  of  air  to  remove  offending 
matter  from  the  lungs  ? 

311.  312.  Illustrate. 

313.  What  is  removed  from  the  lungs  besides  carbon? 

314.  In  what  three  ways  is  air  vitiated? 

CHAPTER  VII. 

315.  How  does  temperature  of  the  air  affect  the  removal  of  waste  ' 

316.  What  sensations  are  experienced  in  warm  weather?     Why? 

317.  .How  does  mountain  air  affect  breathing? 

318.  What  impurities  in  some  mines?     What  their  effect? 

319.  Does  the  state  of  the  system  affect  the  removal  of  waste  ? 

320.  How  do  diseases  of  the  lungs  impair  respiration? 

321.  What  occurs  in  lung  fever  and  some  other  diseases? 

322.  What  effect  have  mental  states  ? 

CHAPTER  VIII. 

323.  What  does  respiration  imply  in  regard  to  the  chest  ? 

324.  What  organs  are  passive  in  respiration  ? 

325.  326.  What  apparatus  is  active,  and  how  does  it  act  ? 
327,  328.  How  may  the  motions  of  the  ribs  be  impeded? 

329,  330,  331.  How  may  the  motions  of  the  diaphragm  be  impeded  ? 

CHAPTER  IX. 

332.  What  is  the  natural  principle  of  beauty  ?     What  the  ideal  ? 

333.  What  is  the  relation  of  the  chest  to  the  body  ? 

334.  What  principle  of  utility  is  to  be  considered  in  the  size  of  the 
chest? 

335.  What  is  live  real  standard  of  beauty  of  the  chest  and  wa:st  ? 

336.  When  do  we  find  the  waist  of  natural  shape  ?     What  is  it? 

337.  What  is  the  effect  of  close  and  small  dresses  on  the  chest  / 

338.  What  upon  respiration  ? 

339.  340.  How  does  pressure  affect  the  bony  frame  ?     The  ribs  ? 

CHAPTER  X. 

341.  What  disorders  may  impede  the  action  of  the  diaphragm? 

342.  What  is  the  average  number  of  respirations  in  a  minute  7 

35 


410  QUESTIONS    ON 

343.  What  is  the  average  capacity  of  a  man's  lungs,  when  not  ex- 
panded ?     How  much  air  is  received  at  each  inspiration  ? 

344,  345.  Does  the  quantity  of  air  inspired  correspond  to  the  amount 
of  wasfsj  to  be  removed? 

346.  What  are  nearly  the  proportions,  of  blood,  of  air,  and  of  waste  ? 

CHAPTER  XI. 

347,  348.  How  much  air  is  unfitted  for  respiration  in  a  minute  by 
the  loss  of  oxygen  ?     What  per  cent,  of  carbonic  acid  gas  unfits  air  for 
respiration  ?     How  much  does  one  person  unfit  in  this  proportion  in 
one  minute  ? 

349.  How  mucli  watery  vapor  will  air  at  32°  contain?     How  much 
at  65°?  at  70°? 

350.  When  is  this  vapor  condensed?     When  frozen  ? 

351.  How  much  air  will  the  vapor  from   the  lungs  saturate  in  a 
minute? 

352.  What  other  source  of  moisture  ? 

353.  What  is  the  average  amount  of  insensible  perspiration   in  a 
minute  ? 

354.  In  what  three  ways  is  air  unfitted  for  respiration? 

CHAPTER  XIT. 

355.  How  much  fresh  air  ought  to  be  supplied   to  each  person  per 
minute  ? 

356.  357.  What  is  neglected  in  dwellings  and  public  rooms  ?    What 
partially  remedies  the  neglect? 

358,  359.  Mention  a  deficiency  in  sitting  rooms ;  in  sleeping  rooms. 

360.  Deficiencies  in  public  boarding  houses,  &c. 

361,  362.  363.  What  other  places  are  still  more  crowded  ? 

CHAPTER  XIII. 

364.  How  large  a  workshop  is  thought  sufficient  for  six  or  eight  men  ? 
'365,  366.  What  other  places  are  badly  ventilated? 

367.  What  facts  are  mentioned  respecting  churches? 

368.  And  halls  ? 

369.  What  facts,  respecting  school-houses? 

370.  To  what  does  habit  reconcile  us? 

371.  Do  persons  entering  a  crowded  room,  and  those  living  in  it,  have 
the  same  sensations? 

372.  What  fails  to  be  accomplished  in  such  cases? 

373.  For  what  do  well-arranged  means  of  ventilation  provide? 

CHAPT-ER  XIV. 

374.  .What  correspondence  between  respiration  and  vital  energy? 

375.  What  illustration  do  hybernating  animals  afford? 

376.  What  animals  are  most  active  ?     What  most  sluggish  ? 

377.  In  the  same  class,  who  have  a  lower  life  than  others? 

378.  How  does  consumption  waste  the  flesh  and  strength  ? 

379.  380.  What  is  a  necessary  result  of  imperfect  respiration  ? 
381.  Why  does  sleep  sometimes  fail  to  refresh?     382.  Illustrate 


411 


CHAPTER  XV. 


383.  What  effect  has  corrupted  air  on  a  crowded  audience  ? 

384.  What  effect  has  an  ill- ventilated  school-room  on  the  children? 
385    What  occurred  in  the  Black-hole  of  Calcutta  ?     What  is  the  dif- 
ference between  this  result  and  the  faintness  of  a  crowded  room? 

386.  What  effect  has  pure  carbonic  acid  gas  ? 

387.  What  is  a  common  source  of  danger  from  carbonic  acid  gas? 

388.  How  does  drowning  produce  death? 

389.  What  are  some  more  remote  effects  of  bad  air? 

390.  Why  are  females  more  susceptible  of  consumption  than  males  7 

CHAPTER  XVI. 

391.  How  does  the  privation  of  air  affect  different  animals! 

392.  What  power  can  man  acquire  by  long  practice  ? 

393.  What  necessity  is  imposed  on  all  animals  ? 

394.  395.  Is  there  any  natural  deficiency  of  air? 

396.  What  reciprocal  offices  do  animals  and  vegetables  perform  ? 

397.  When  do  vegetables  consume  carbonic  acid  ?     When  give  it 
out? 

398.  When  are  house-plants  salutary  ?     When  injurious  ? 


PART    IV.  , 

ANIMAL  HEAT. 

CHAPTER  I. 

399.  What  is  the  temperature  of  most  animals  compared  with  that 
of  the  surrounding  medium  ?     400,401.  What  illustrations? 

402.  What  were  the  experiments  of  Sir  Charles  Blagden  ? 

403.  What  tendency  is  almost  universal?     404.  Illustrate. 

405.  What  exception  to  this  tendency  ? 

406.  What  effects  would  follow,  if  living  bodies  could  not  retain  a 
uniform  temperature  ? 

CHAPTER  II. 

407.  How  is  the  heat  of  the  living  body  affected  by  cold  bodies? 

408.  How  does  the  law  of  heat  among  dead  substances  differ  from 
this? 

409.  What  is  the  origin  of  the  heat  in  living  bodies  ? 

410.  Into  what  classes  are  animals  divided  in  relation  to  heat? 

411.  From  what  difference  of  structure  does  this  difference  of  tem- 
perature arise  ? 

412.  Does  the  same  distinction  occur  among  the  inhabitants  of  the 
sea  ? 

413    What  conditions  are  necessary  to  maintain  this  internal  heat! 


412  QUESTIONS    ON 


CHAPTER  III. 

414.  With  what  process  is  internal  heat  connected  ? 

415.  What  do  we  understand  by  the  term  latent  heat? 

416.  What  is  given  us  as  a  general  law  of  matter? 

417.  What  is  the  difference  between  sensible  and  specific  heat  ? 

418.  How  does  combustion  illustrate  this  distinction  ? 

419.  Apply  these  principles  to  explain  animal  heat. 

420.  What  was  once  generally  believed? 

421.  What  is  the  process  now  generally  maintained  ? 


CHAPTER  IV. 

422.  How  does  exercise  increase  animal  heat? 

423.  How  does  impeded  circulation  affect  the  temperature  ? 

424.  How  is  this  internal  combustion  maintained?    How  impeded  I 

425.  What  hindrances  are  enumerated? 

426.  Why  do  persons  in  a  crowded  room  grow  cold? 

427.  Who  need  most  external  protection  from  cold,  and  why  ? 

428.  What  is  needed  to  maintain  this  internal  combustion  besides 
air?     How  is  it  supplied? 

429.  Who  can  best  resist  external  cold? 

430.  Which  protects  from  cold  best,  alcohol  or  food  ? 

431.  Which  warms  most,  flesh  or  bread?     What  necessity  has  na- 
ture met  ^nd  supplied  ? 

CHAPTER  V. 

432.  What  other  influences  affect  the  supply  of  heat  ? 

433.  How  do  different  states  of  the  system  modify  the  quantity  of 
heat? 

434.  What  lessens  the  production  of  heat  ? 

435.  What  difference  at  different  periods  of  life  ? 

436.  How  does  sleep  affect  the  power  of  producing  heat  ? 

"  437.  On  what  does  the  amount  of  heat  in  combustion  depend  ? 

438.  How  mur-h  heat  is  generated  in  the  body  in  a  day? 

439.  What  prevents  an  increase  of  temperature  in  the  body? 

440.  How  does  heat  escape  from  the  body? 

441.  What  active  power  does  the  skin  exert?     In  what  way  does 
perspiration  cool  the  body? 

442.  How  do  Blagden's  experiments  illustrate  this  principle? 

443.  What  beautiful  adaptation  is  mentioned  ? 

444.  What  is  the  winter  constitution  ?     The  summer  constitution  ? 

445.  What  were  the  experiments  of  Dr.  Edwards  ? 

446.  Why  is  the  transition  from  the  cold  of  winter  to  the  heat  of 
summer  unattended  with  suffering  ? 

447.  Who  especially  need  the  protection  of  thick  clothing  in  win- 
ter ? 


413 

PART  V. 

SKIN. 

CHAPTER  I. 

448.  What  protects  the  organs  of  life  from  external  agencies  I 

449.  Describe  the  cuticle.     450.  Is  it  subject  to  change  1 

451.  When  does  it  become  thick  and  tough? 

452.  Will  every  kind  of  friction  produce  this  effect? 

453.  What  is  the  effect  of  friction  gradually  applied  ? 

454.  To  what  extent  may  the  outer  skin  be  made  thick  and  tough  f 

455.  How  does  new  and  coarse  work  affect  the  hands  ? 

456.  How  are  corns  produced  ? 

CHAPTER  II. 

457.  What  protection  does  the  cuticle  afford  ? 

458.  What  other  parts  grow  out  of  the   cuticle? 

459.  Describe  the  nail. 

4GO.  What  is  the  structure  of  the  hair  ? 

461.  How  is  the  scarf-skin  kept  fresh  and  new  ? 

462.  Where  is  the  seat  of  color?     What  is  the  rete  mucosum? 

463.  What  produces  various  hues  in  some  animals  ? 

464.  Describe  the  true  skin  ? 

465.  When  is  the  surface  florid?     What  may  make  it  more  sof 
Less  so  ? 

466.  What  sense  and  what  degree  of  sensibility  are  in  the  skin  ? 

467.  What  is  directly  under  the  skin  ?     Where  thick  ?     Where  thin  t 

CHAPTER  III. 

468.  In  what  form  does  the  waste  of  the  body  escape  through  the 
skin?     In  what  quantity?     What  was  Sanetorius's  experiment? 

469.  At  what  results  did  Seguin  arrive  ? 

470.  How  can  this  insensible  perspiration  be  made  manifest? 

471.  What  is  sensible  perspiration?     Which  is  constant?     Which 
greatest  in  the  whole  amount  ? 

472.  473,  474.  Relate  the  experiments  at  the  Phoenix  gas  works. 

475.  How  is  the  weight  of  the  body  kept  uniform? 

476.  What  is  the  average  amount  of  cutaneous  exhalations  ?     What 
produce  variations? 

CHAPTER  IV. 

477.  What  external  circumstances  modify  the  amount  of  perspira- 
tion ? 

478.  What  is  the  effect  of  the  atmosphere  saturated  with  moisture  t 

479.  Describe  the  minute  structure  of  the  perspiratory  organs. 

35* 


414  QUESTIONS   ON 

480.  Do  all  animals  possess  the  perspiratory  apparatus? 

481.  What  provision  for  keeping  the  skin  soft  and  smooth? 

482.  What  properties  has  this  oily  secretion? 

483.  What  will  render  the  skin  stiff  and  hard? 

484.  What  kind  of  clothing  is  injurious?  and  why? 

485.  What  kinds  of  hats  are  too  close  ? 

CHAPTER  V. 

486.  What  connection  exists  between  the  skin  and  the  internal  or- 
gans of  the  body  ? 

487.  What  facts  illustrate  this  connection  ? 

488.  How  are  the  lungs  and  skin  related  ?     What  are  their  sympa- 
thies? 

489.  What  relations  exist  between  the  skin  and  the  digestive  organs  ? 

490.  491.  What  internal  organ  is  most  liable  to  suffer  when  the  cu- 
taneous circulation  is  disturbed  ? 

492.  What  may  always  be  inferred,  when  the  skin  is  dry  ? 

CHAPTER  VI. 

493.  When  does  the  skin  act  as  an  absorbent  ?   494.  Give  illustration. 

495.  State  the  case  of  absorption  in  a  hot  bath,  and  that  of  Ann  Moore 

496.  What  other  substances  may  be  absorbed  ? 

497.  498.  What  facts  prove  cutaneous  absorption  ? 

499.  At  what  limes  is  the  absorbing  power  most  active? 

500.  What  stimulates  the  cutaneous  absorbents  ? 

CHAPTER  VII. 

501.  Is  the  sense  of  touch  uniform  over  the  whole  body? 

502.  When  is  cutaneous  sensibility  most  acute?     In  what  persons? 

503.  On  what  does  the  facility  of  cutaneous  sensation  depend  ? 

504.  What  can  education  do  for  the  sense  of  touch  ? 

505.  How  is  the  loss  of  one  sense  compensated? 

506.  What  illustrations  do  the  blind  and  some  others  furnish  ? 

507.  What  blunt  the  sensibility  of  the  skin? 

CHAPTER  VIII. 

508.  How  does  the  skin  prevent  the  effects  of  heat  and  cold? 

509.  What  tendency  is  constant?     What  its  effect? 

510.  Why  is  perspiration  a  cooling  process? 

511.  How  do  different  states  of  the  air  affect  its  cooling  powers? 

512.  In  what  state  does  the  skin  perform  its  functions  well? 

513.  How  do  some  states  of  disease  affect  the  skin? 

514.  Can  we  measure  temperature  correctly  by  touch? 

515.  What  illustration  may  two  travellers  furnish? 

516.  What  bodily  and  mental  states  favor,  and  what  impede  ijhe 
healthy  action  of  the  skin  ? 


JARVIS'S    PRACTICAL    PHYSIOLOGY.  415 

CHAPTER  IX. 

-4. 

517.  What  three  offices  does  the  skin  perform? 

518.  Do  the  functions  of  the  skin  require  the  aid  of  clothing? 

519.  What  is  the  practical  view  of  the  case? 

520.  Do  all  parts  of  the  skin  protect  equally  well  ? 

521.  What  illustration  is  drawn  from  the  dress  of  the  two  sexes  ? 

522.  What  from  the  Indian?     From  the  Highlander? 

523.  524,  525.  Give  the  facts  and  the  conclusions  to  which  they  lead. 

526.  What  practical  suggestions  are  given  ? 

527.  What  effects  do  habits  of  dress  in  different  periods  of  life  pro- 
duce? 

CHAPTER  X. 

528.  529,  530.  What,  besides  habit,  should  influence  the  amount  of 
clothing? 

531.  Can  a  general  rule  be  given?     532.  What  general  directions? 
533., What  are  the  effects  of  too  little  clothing? 

534.  What  power  comes  from  habitual  exposure  ? 

535.  Can  all  persons  acquire  this  power  suddenly  ? 

536.  Why  do  infancy  and  old  age  require  more  clothing  than  the 
middle  period  of  life? 

537.  How  can  even  the  feeble  gain  their  power  of  endurance? 

CHAPTER  XI. 

538.  What  qualities  should  clothing  possess  ? 

539.  Why  are  loose  garments  warmer  than  tight? 

540.  What  are  the  objections  to  inner  garments  of  linen  ? 

541.  What  are  the  good  qualities  of  cotton  ? 

542.  What  qualities  has  silk  for  inner  garments  ? 

543.  What  qualities  recommend  woollen  garments?     What  bad  ef- 
fects on  some1? 

544.  Against  what  should  the  skin  be  guarded?     What  is  the  best 
protection  ? 

CHAPTER  XII. 

545    What  fact  proves  the  good  effects  of  flannel  ? 

546.  What  other  measures  were  used  for  the  health  of  seamen  ? 

547,  548,  549.  What  do  inner  garments  retain  ? 
550,  551    What  changes  should  be  practised  ? 

552.  How  should  beds  and  bed-clothes  be  treated  ? 

553.  What  objectionable  practice  prevails  on  board  canal-boats  ? 

554.  What  injurious  necessity  exists  in  some  dwellings  ? 

CHAPTER  XIII.. 

555.  What  change  of  the  cuticle  goes  on  constantly? 

556.  What  effect  of  the  warm  bath  is  mentioned  ? 

557.  What  neglect  are  many  persons  guilty  of? 


416  QUESTIONS    ON 

558.  What  difference  between  their  skins  and  that  of  those  who 
bathe  ? 

559.  What  daily  practice  does  perfect  health  require  ?     Is  water 
alone  sufficient  1 

560.  What  custom  has  prevailed  in  some  nations  ? 

561.  In  what  are  the  English  and  Americans  surpassed  by  some 
other  nations? 

562.  Describe  different  kinds  of  baths. 

CHAPTER  XIV. 

563.  What  bath  is  suitable  in  good  health  ? 

564.  What  maybe  easily  used  instead  of  a  plunge  bath? 

565.  What  are  a  proper  time  and  manner  of  taking  the  cold  bath  ? 

566.  Is  the  time  required  for  the  bath  lost  time  ? 

567.  Who  may  not  safely  use  the  cold  bath? 

568.  What  is  occasionally  necessary? 

CHAPTER  XV. 

569.  What  are  the  good  effects  of  cold  bathing? 

570.  What  confirmation  does  Dr.  A.  Combe  give  ? 

571.  What  is  recommended  to  the  weakly? 

.     572.  What  condition  of  the  stomach  should  be  regarded? 

573.  What  is  the  best  time  for  the  bath  ? 

574.  What  common  notion  is  erroneous  ?    575.  Give  an  illustration 

576.  To  what  else  may  the  same  principles  be  applied  ? 

CHAPTER  XVI. 

577.  What  effect  has  bathing  on  the  nervous  sensibility?     Why  is 
a  burn  on  the  skin  often  more  dangerous  than  a  deeper  wound  ? 

578.  What  neglect  blunts  the  sensibility  of  the  skin?     How  does 
cleanliness  increase  it? 

579.  State  the  case  of  Laura  Bridgman. 

580.  What  is  the  practice  of  Esquirol  ? 

581.  What  has  been  shown  in  regard  to  the  structure  and  offices  of 
the  skin  ? 

582.*  What  duties  belong  to  every  human  being? 


PART  VI. 

BONES,  MUSCLES,  EXERCISE,  AND  REST. 
CHAPTER  I. 

583.  What  is  the  structure  of  the  bones  ?     When  are  they  strong  ? 

584,  585.  What  is  the  condition  of  the  bones  at  different  periods  of 
life? 


JARVIS'S   PRACTICAL   PHYSIOLOGY.  417 

586.  With  what  organs  are  the  bones  supplied  ? 

587.  How  are  broken  bones  re-united? 

588.  What  shows  the  process  of  absorption  and  deposition? 

589.  What  effect  has  exercise  on  the  bones  ? 

590.  What  stunts  the  growth?     How  may  the  bones  of  childhood 
be  distorted  ?     What  injury  is  sometimes  done  in  schools  ? 

591.  What  causes  the  rickets?     Who  are  exposed  to  this  disease? 

592.  What  is  the  internal  structure  of  the  bones? 

CHAPTER  II. 

593.  How  many  bones  in  the  human  frame?     What  their  shapes  ? 

594.  Describe  the  principal  parts  of  the  bony  frame.     The  skull. 

595.  Describe  the  chest ;  the  spine  ;  a  vertebra. 
590.  How  are  the  vertebrae  distributed? 

597.  What  substance  between  the  vertebrae?     How  does  it  aid  in 
bending  the  spine  ?     Why  is  a  man  shorter  at  night  than  in  the  morn- 
ing? 

598.  What  is  the  shape  of  the  spine? 

599.  Describe  the  pelvis. 

CHAPTER  III. 

600.  Describe  the  upper  extremities:  shoulder  blade  :  collarbone, 
arm  :  wrist :  hand. 

601.  Describe  the  lower  extremity:  the  foot. 

602.  Describe  composition  and  form  of  the  foot. 

603.  How  may  the  benefit  of  tlie  arch  be  shown  ? 

604.  How  do  we  avoid  ajar  in  jumping  from  an  elevation? 

605.  What  is  the  natural  shape  of  the  foot?      What  the  artificial? 

CHAPTER  IV. 

606.  What  office  do  the  joints   perform  ?     What  are   the  different 
kinds  of  joints? 

607.  Describe  the  hip  joint. 

608.  Describe  the  upper  joints  of  the  neck.  „ 
•  609,  610.  What  contrivance  to  prevent  jars  and  friction? 

611.  What  keeps  the  joints  from  wearing  out?     How  are  they  kept 
moist  ? 

612.  How   are   the   bones  held   together?     What  is   the   synovial 
membrane  ? 

613.  What  is  a  sprain? 

614.  How  are  the  bones  dislocated  ? 

CHAPTER  V. 

615.  Describe  the  muscles.     What  is  their  office  ? 

616.  What  is  their  power  ?     What  is  their  action? 

617.  How  are  they  arranged? 


418  QUESTIONS   ON 

618.  Describe  the  muscles  that  lift  the  shoulder ;  that  bend  the  elbow, 
that  draw  the  arm  forward  ;  that  bend  the  wrist.     What  is  the  tailor's 
muscle  ?     What  muscles  bend  the  hip  joint?      What  muscles  straight- 
en the  leg? 

619.  Describe  the    Trapezium  muscle.     Describe  the  muscle  that 
straightens  the  elbow  ;  that  straightens  the  hip  ;  that  bends  the  knee  ; 
that  straightens  the  ancle. 

620.  Describe  the  .muscles  that  draw  the  shoulder  forward;  that  roll 
the  thigh  outward. 

CHAPTER  VI. 

621.  What  are  the  shapes  of  the  muscles? 

622.  How  does  the  diaphragm  act?     The  heart?     The  oesophagus  ? 

623.  What  is  done  by  the  muscles? 

624.  How  are  the  muscles  attached  ?     Describe  some  of  the  muscles 
on  the  face  ? 

625.  How  are  the  muscles  placed  in  regard  to  the  bones? 

626.  What  occurs  in  the  muscles  when  they  act  ?     How  can  you 
feel  their  action  ?  „ 

627.  When  can  the  action  of  certain  flat  muscles  be  perceived  ? 

628.  How  many  sets  of  muscles  has  each  hinge  joint?     What  is  the 
office  of  each  set  ? 

629.  H  »w  can  you  perceive  the  alternate  working  of  the  muscles 
that  move  the  fingers  ? 

630.  How  is  the  variety  of  motions  produced  in  the  ball  and  socket 
joints,  and  in  some  others? 

CHAPTER  VII. 

631.  What  muscles  act  at  disadvantage  ?     632.  Illustrate  in  fore-arm 

633.  Why  is  this  loss  of  power  made  ?     How  is  it  provided  for  ? 

634.  Give  another  illustration. 

635.  Specify  instances  of  rapid  muscular  motion. 

630.  Specify  instances  of  action  by  a  concert  of  muscles. 

637.  What  power  do  performers  on  the  piano-forte  acquire? 

638.  What  precision  does  a  skilful  violinist  acquire  ? 

639.  What  illustration  may  be  drawn  from  the  act  of  writing? 

640.  %What  does  this  control  over  muscular  action  enable  men  to  do  . 
Give  an  illustration. 

CHAPTER  VIII. 

641.  To  what  is  the   strength  of  muscles  generally  proportioned'1 
What  exceptions  ? 

642.  How  does  the  strength  of  man  compare  with  that  of  a  flea? 

643.  To  what  does  muscular  power  correspond  ? 

644.  For  what  purpose  is  muscular  power  given? 

645.  How  do  the  muscles  of  the  active  and  inactive  differ? 

646.  647.  Give  the  first  illustration.     Second.     Third. 

648.  What  employments  develop  the  muscles  best?     Why? 

649.  What  employments  develop  some  muscles  disproportionately? 
Why?     How  is  this  shown  in  other  animals  ?  in  birds? 


419 


CHAPTER 

650.  Why  are  some  persons  strong  i 

651.  Give  illustration. 

652.  How  are  the    size  and  strength  of  the  muscles  preserved  T 

653.  Illustrate. 

654.  What  collateral  advantages  result  from  muscular  exercise? 

655.  What  connection  has  digestion  with  exercise  ? 

656.  How  does  exercise  aid  the  circulation  ?     657.  How  respiration  ? 

658.  How  does  exercise  increase  animal  heat? 

CHAPTER  X. 

659.  How  does  a  muscle  gain  size  and  strength  by  exercise? 

660.  What  other  benefit  of  exercise  is  mentioned  ? 

661.  What  difficulties  may  be  removed  by  exercise  ?     662.  Give  the 
history  of  the  robust  boy? 

663.  How  is  each  one  to  determine  his  proper  degree  of  exercise? 

664.  What  results  indicate  too  much  action  1     What  result  indicates 
enough  ? 

665.  What  is  said  of  the  permanence  of  muscular  action? 

CHAPTER  XI. 

666.  667,  668.  How  should  the  feeble  begin  to  exercise  ?     Give  an 
illustration. 

669.  When   do   debilitated  students,  &c.,  derive   no  benefit    from 
labor  ? 

670.  What  is  recommended  to  invalids  going  to  sea  for  health  ? 

671.  Why  have   not   gymnastic  exercises    produced   the   expected 
result? 

CHAPTER  XII. 

672.  What  kind  of*  exercise  is  best?     673.  How  should  we  walk? 
674.  What  exercises  are  allowed  to  boys?     675.  How  are  girls  re- 
stricted ? 

676.  What  custom  prevails  among  English  women? 

677.  What  employments  may  be  combined  with  walking? 

678.  In  what  circumstances  is  dancing  a  good  exercise  ? 
679,680  681.  Give  the  suggestions  relating  to  the  time  of  taking 

exercise. 

CHAPTER  XIII. 

682.  Where  should  exercise  be  taken?     Why? 

683.  What  kind  of  weather  may  prevent  exercise  abroad  ? 

684.  Are  any  exempted  from  the  need  of  exercise  ? 

685.  686.  What,  besides  the  quantity  of  exercise,  demands  attention  1 

687.  Are  the  consequences  of  neglect  sudden  ?  or  remote  ?    Are  they 
the  less  certain? 

688.  What  laws  are  established  ? 


420  QUESTIONS    ON 


CHAPTER  XIV. 

689.  Is  the  exercise  which  health  requires,  the  limit  of  muscular 
power  ? 

690.  What  questions  are  important  for  the  laborer? 

691.  How  can  the  laborer  know  he  has  overworked  ?     How  long 
may  he  increase  his  exertions  ? 

692.  How  can  he  maintain  the  fulness  of  his  strength  ? 

693.  Has  man  an  indefinite  power  of  endurance? 

694.  How  is  premature  old  age  sometimes  induced  ? 

695.  What  is  a  common  effect  of  overworking  ?     Illustrate. 

696.  Among  what  class  is  the  length  of  life  shortest? 

697.  May  not  other  circumstances  account  for  the  shorter  life  of  the 
day-laborer  and  sailor  ? 

CHAPTER  XV. 

698.  Does  excessive  labor  for  a  short  period  produce  the  same  kind 
of  result? 

699.  What  permanent  injury  often  results  ?     Illustrate. 

700.  Who  suffers  most  from  great  exertion  ? 

701.  When  does  a  man  acquire  full  strength?     What  is  the  ordei 
of  development  of  power? 

'CHAPTER  XVI. 

702.  Why  does  labor  require  healthy  organs  of  digestion  and  nutri- 
tion ? 

703.  What  kind  of  food  does  labor  require  ?     Why? 

704.  What  kind  of  food  should  a  laboring  man  eat?     Why  ? 

705.  Can  a  man  labor  well  whose  skin  and  lungs  are  not  in  a  healthy 
condition?     Why? 

706.  How  do  diseases  of  the  heart  unfit  for  labor? 

707.  How  do  the  state  and  health  of  the  brain  and  mind  affect  the 
ability  to  labor? 

708.  709.  What  is  the  proper  state  of  the  brain  and  mind  while 
taking  exercise  ? 

CHAPTER  XVII. 

710.  What  motive  does  labor  for  profit  require  ? 

711.  What  are  the  effects  of  hope  and  despair  on  labor? 

712.  What  of  confidence,  and  of  doubt? 

713.  What  is  the  effect  of  cheerfulness  and  of  melancholy? 

714.  What  is  the  effect  of  alcoholic  liquors? 

CHAPTER  XVIII. 

715.  What  is  the  natural  form  of  the  spine  ?     How  is  the  head  held  ? 

716.  Describe  the  muscles  of  the  back? 

717.  How  does  a  curvature  of  the  spine  affect  the  muscles  of  the 
back? 


JARVIS'S    PRACTICAL    PHYSIOLOGY. 

718.  What  is  said  of  the  strength  of  the  back?     What  illustration? 

719.  What  is  the  best  position  of  the  spine  for  burdens  on  the  head? 

720.  How  is  the  head  carried  most  easily?     Explain. 

721.  What  is  said  of  the  centre  of  gravity  in  carrying  burdens? 
Give  illustrations. 

722.  What  farther  illustrations? 
723    Explain  this  farther. 

724.  What  is  said  of  the  grace  of  this  attitude  ? 

CHAPTER  XIX. 

725.  What  is  the  best  attitude  for  walking?     Why? 

726.  What  for  labor  ?     What  illustration  ? 

727.  What  other  persons  act  best  in  this  position? 

728.  How  is  the  lateral  curvature  of  the  spine  induced  ? 

729.  How  is  the  forward  curvature  produced  ?     Who  are  liable  toil? 

730.  Who  are  exposed  to  this  curvature  ?     How  ? 

731.  How  is  the  spine  affected  by  the  position  of  persons  writing? 
or  reading  ? 

732.  What  is  Dr.  Warrens'  opinion? 

733.  Why  are  boys  less  subject  to  curved  spine  than  girls? 

734.  How  are  the  lungs  affected  by  curved  spine? 

735.  736.  How  is  the  spinal  cord  ? 

CHAPTER  XX. 

737.  What  law  of  nature  is  almost  universal? 

738.  What  disadvantages  has  night  labor?     Illustrate. 

739.  What  is  the  experience  of  milkmen  and  others  who  devote  a 
part  of  the  night  to  their  business? 

CHAPTER  XXI. 

740.  What  natural  indication  does  man  need  to  follow? 

741.  Can  the  quantity  of  sleep  be  fixed  by  a  general  rule  ? 

742.  What  shows  night  to  be  the  season  of  sleep? 

743.  What  is  the  uniform  effect  of  loss  of  sleep  ? 

744.  Why  does  sleep  require  an  increase  of  clothing? 

745.  What  are  the  conditions  necessary  for  refreshing  sleep  ? 

746.  Does  the  digestive  process  go  on  well  in  sleep? 


PART  VII. 
BRAIN  AND  NERVOUS  SYSTEM. 

CHAPTER  I. 

747.  Describe  the  brain. 

748.  Into  what  portions  is  the  brain  divided? 

749.  What  are  the  offices  of  the  membranes  which  divide  the  brain 

750.  What  is  the  spinal  cord,  and  its  position  ? 

36 


422  QUESTIONS    ON 

751.  How  is  every  organ  connected  with  the  brain? 

752.  What  two  kinds  of  nerves,  and  what  their  offices  ? 

753.  How  is  it  shown  that  they  perform  separate  offices  ? 

754.  How  do  these  two  kinds  of  nerves  differ  in  their  termination? 

CHAPTER  II. 

755.  What  three  things  are  necessary  for  sensation  ? 

756.  What  happens  when  the  foot  is  asleep  ? 

757.  How  do  the  nerves  pass  from  the  brain  to  the  trunk  and  ex- 
tremities ? 

758.  How  do  injuries  to  the  spine  affect  the  nerves?     759,  760,  761. 
Give  illustrations. 

762.  What  does  the  case  of  Mr.  J.  illustrate? 

CHAPTER  III. 

763.  Why  does  the  brain  refer  sensations  to  the  end  of  the  nerves  ? 

764.  If  the  trunk  of  the  nerve  is  irritated  or  injured,  to  what  part  is 
the  impression  referred  ? 

765.  Where  is  the  seat  of  disease  in  the  tic  douloureux  ?     766.  Il- 
lustrate by  Miss  W.'s  case. 

767.  Where    do  the  nerves  of  special  sense  receive  impressions'? 
How  can  an  impression  like  that  of  light  be  made  on  the  brain,  when 
the  eye  is  closed  ? 

768.  What  illustrations  are  derived  from  the  sense  of  hearing,  and 
of  taste? 

769.  What  is  the  effect  of  exciting  a  nerve  in  any  part  of  its  course  ? 

770.  Illustrate. 

CHAPTER  IV. 

771.  What  fact  does  the  last  section  explain? 

772.  How  is  muscular  motion  excited  naturally?     How  artificially? 
Illustrate. 

773.  Where  is  sensation  ?     What  is  its  immediate  cause  ?     Where 
is  a  true  sensation  excited?     Where  a  false  one  ?     How  do  the  cham- 
ber bells  in  a  hotel  illustrate  true  and  false  sensations? 

774.  What  instances  of  false  sensations  are  mentioned? 

775.  Is  the  communication  through  the  nerves  rapid? 

776.  What  organs  are  voluntary  ?     Why  so  called  ?      What  are  in 
voluntary?     Are  these  supplied  with  nerves? 

777.  Do  the  voluntary  organs  ever  act  involuntarily  ?     State  cases. 

778.  What  voluntary  motions  become  apparently  involuntary? 

779.  Why  do  familiar  motions  exhaust  less  than  others  ?     Illustrate. 

780.  On  what  does  the  power  of  every  organ  to  act  depend  ? 

CHAPTER  V. 

781.  Why  is  the  brain  carefully  guarded  from  injury? 

782.  The  brain  is  the  seat  of  what? 

783.  Is  the  brain  sensitive?     Illustrate. 

784.  What  is  the  effect  of  pressure  on  the  brain? 


JARVIS'S  PRACTICAL  PHYSIOLOGY.         423 

785.  Relate  a  case  recorded  by  Sir  Astley  Cooper. 

786.  Is  the  brain  subject  to  growth  and  decay1?     With  what  appara- 
tus is  it  furnished?     What  part  of  the  blood  of  the  body  does  the  brain 
receive  ? 

787.  What  effect  has  the  action  of  the  brain  on  its  blood-vessels? 

788.  When  does  the  brain  require  rest? 

789.  What  is  the  natural  rest  of  the  brain?     What  kind  of  sleep 
refreshes  the  brain  most? 

CHAPTER  VI. 

790.  What  is  the  proper  season  for  mental  labor  ?     For  mental  re- 
pose? 

791.  What  do  some  students  practise ?     With  what  effect?     When 
has  the  brain  naturally  the  greatest  power  for  labor? 

792.  What  effect  has  proper  exercise  on  the  brain?     What  effect 
has  excessive  exercise  ? 

793.  What  relation  exists  between  the  brain  and  other  organs? 

794.  What  between  the  brain  and  heart?     795.  Between  the  brain 
and  lungs?     796.  Between  the    brain  and  stomach?     797.  Between 
the  brain  and  muscles? 

798.  How  does  alcohol  affect  muscles?     799.  Is  this  permanent? 

800.  Illustrate. 

801.  Why  is  the  drunkard,  when  sober,  exposed  to  accidents? 

CHAPTER  VII. 

802.  How  does  the  mind  communicate  with  the  external  world? 
8U3.  What  fixes  a  limit  to  the  action  of  the  human  mind?     • 

804.  What  reciprocal  influences  are  exerted  by  the  brain  and  the 
mind  ? 

805.  Mention  some  specific  influences. 

806.  State  the  case  of  a  child. 

807.  What  is  the  effect  of  indigestion  and  nausea? 

808.  How  does  excessive  eating  affect  mental  action?     How  does 
hunger  ? 

809.  How  are  the  moral  powers  and  affections  influenced  by  the 
stomach  ?     Illustrate. 

810.  What  effects  are  ascribed  to  cheerfulness  ?    What  to  sorrow  and 
care  ? 

811.  What  feelings  favor  digestion?     What  feelings  retard  it? 

812.  What  connection  has  health  with  cheerfulness? 

CHAPTER  VIII. 

813.  What  operations  does  the  brain  superintend  ?     How  far  is  it 
under  our  control  ?     How  far  are  we  responsible  for  its  action  ? 

814.  When  does  the  brain   perform  its  offices  well  ?     When   not 
well  ? 

815.  When  can  the  brain  superintend  more  than  one  operation  at  a 
time  ?     When  only  one  ? 


424  QUESTIONS    ON 

816.  When  can  the  brain  superintend  only  the  involuntary  opera 
tions  ? 

817.  Explain  this  by  the  musician. 

818.  In  what  conditions  can  the  mind  be  concentrated  on  a  subject? 

819.  What  faults  in  many  school-rooms  interrupt  study? 

820.  What  further  faults  are  mentioned  ? 

821.  Why  is  fatigue  incompatible  with  mental  labor? 

CHAPTER  IX. 

822.  823.  How  do  moral  feelings  affect  mental  attention  ? 

824.  What  illustration  does    the    school-room  furnish?     825.  What 
Other  illustrations  ? 

826.  What  seeming  exceptions  are  mentioned  ? 

827.  How  are  they  reconciled  with  the  general  principle  ? 

828.  What  do  these  disturbing  influences  require  ? 

829.  What  motives  for  study  may  interrupt  it  ?     830.  Illustrate. 

831.  What  motives  aid  the  mind  in  fixing  attention  on  a  subject? 

CHAPTER  X. 

832.  What  differences  exist  in  the  various  faculties  of  the  same  per- 
son?    Of  different  persons?     What  is  the  cause  of  this  difference  ? 

833.  How  are  the  mental  and  moral  powers  strengthened  ?     What 
is  the  purpose  of  education  ?     In  what  order  do  the  powers  appear? 

834.  How  is  the  child  prepared  for  abstruse  subjects  ? 

835.  What  are  some  characteristics  of  childhood  ? 

836.  Can  the  mind  be  prematurely  strengthened  ? 

837.  What  is  the  effect  of  premature  mental  exertion  ? 

838.  What  dependence  among  the  organs  ?     Illustrate. 

839.  Why  does  the  health  of  students  often  fail  ? 

840.  Is  mental  effort  compatible  with  health  and  long  life? 

CHAPTER  XI. 

841.  Are  the  several  systems  equally  strong  in  the  same  person  ? 
How  can  this  diversity  be  remedied? 

842.  How  can  mental  irregularities  be  remedied?     What  is  often 
done  at  variance  with  the  proper  remedy? 

843.  What  will  be  the  state  of  the  faculties  which  are  exercised  ? 
What  of  those  not  exercised  ? 

844.  What  illustration  is  drawn  from  the  mechanic  arts? 

845.  What  is  the  effect  of  exclusive  cultivation  of  some  of  the  intel- 
lectual powers  ? 

846.  Does  the  same  principle  apply  to  the  moral  powers  ?     Illustrate. 

847.  What  facts  show  that  any  faculty  can  be  strengthened  at  any 
time  of  life  ? 

848.  How  does  constant  use  affect  the  power  of  observation  ? 

849.  Show  how  the  same  principle  applies  to  the  moral  powers. 

850.  What  part  of  this  work  belongs  to  teaching?     What  part  to 
practice  ? 

851.  How  can  true  politeness  be  distinguished  from  the  assumed? 


425 


CHAPTER  XII. 

852.  "Who  are  a  man's  chosen  associates  ?     Why? 

853.  Why  are  men  unused  to  society  often  averse  to  it?     What  is 
the  character  of  people  long  excluded  from  the  world  ? 

854.  How  is  the  acquired  strength  of  the  mind  to  We  preserved  ? 

855.  What  constitutes  completeness  of  character?     What  are  its  ad- 
vantages ? 

856.  What  is  mental  concentration? 

857.  What  is  one  difference  between  a  strong  and  a  weak  mind? 

858.  On  what  does  the  progress  of  a  student  mainly  depend  ? 

859.  Does  the  exercise  of  the  brain  afford  pleasure  ? 

860.  To  what  degree  must  the  brain  be  exercised,  that  it  may  do  a 
full  day's  work  every  day? 

861.  Is  any  thing  gained  by  overworking  the  brain?     Illustrate. 

862.  Does  a  high  mental  excitement  subside,  as  soon  as  the  exertion 
ceases  ?     Illustrate. 

863.  How  should  our  business  and  studies  be  arranged  ?     What  is 
the  fault  of  the  actual  arrangement? 

CHAPTER  XIII, 

864.  What  diversity  is  found  in  the  digestive  organs  ?     What  is  the 
effect  of  eating  indigestible  food  ? 

865.  How  does  the  same  rule  apply  to  the  mind? 

866.  How  are  some  men  affected  by  intense  application  to  subjects 
out  of  their  common  course  ? 

867.  868.  How  do  the  ills  of  the  other  organs  affect  the  brain? 

869.  How  does  great  cold  affect  the  brain?     Great  heat? 

870.  What  abuses  may  lead  to  insanity?     871.  Illustrate. 

CHAPTER  XIV. 

872.  What  is  the  effect  of  misdirected  education? 

873.  What  expectations  may  produce  the  same  effect  ? 

874.  What  is  the  effect  in  some  cases  of  religious  anxiety? 

875.  What  is  the  tendency  of  natural,  or  artificial  appetites,  if  in- 
dulged? 

876.  What  may  be  the  effect  of  irregular  mental  habits  ? 

CHAPTER  XV. 

877.  What  is  day-dreaming  ?     878.  To  what  results  does  it  lead  ? 
879.  What  is  the  effect  of  strong  emotions?     Of  fright?     880.  Of 

uncontrolled  passion? 

881.  How  do  physical  stimulants  affect  the  brain? 

882.  Is  insanity  the  uniform  result  of  these  causes?     Between  what 
extremes  do  they  leave  the  mind  ? 

883.  To  what  extent  is  man  responsible  for  mental  health   and 
strength  ? 

36* 


426  QUESTIONS   ON 


CHAPTER  XVI. 

884.  Where  is  the  eye  placed  ? 

885.  What  is  the  aqueous  humor  ?     What  the  vitreous  ?     The  crys- 
talline lens  ? 

886.  Describe  the  sclerotic  coat ;  the  cornea. 

887.  8'88.  Describe  the  choroid  coat;  the  retina. 

889.  What  are  the  parts  of  the  eye,  beginning  in  front?     Describe 
the  iris ;  the  pupil,  and  its  action. 

890.  Describe  the  lids. 

891.  Describe  the  apparatus  for  the  tears. 

892.  What  happens  sometimes  to  the  lachrymal  canals  ? 

893.  What  sympathies  has  the  lachrymal  apparatus  ? 

894.  What  move  the  eye  1 

895.  What  is  the  cross-eye  ? 

896.  Describe  the  optic  nerve. 

897.  How  is  vision  produced  ? 


CHAPTER  XVII. 

898.  What  is  near-sightedness?     How  may  it  be  avoided? 

899.  What  is  the  state  of  the  lens  ?     What  is  the  effect  of  concave 
spectacles?     How  should  they  be  worn? 

900.  What  is  the  effect  of  single  eye-glasses  ? 

901.  What  is  far-sightedness? 

902.  What  are  some  of  the  diseases  of  the  eye  ? 

903.  How  should  the  eye  be  treated  for  cleansing  ? 

904.  How  is  the  eye  affected  by  air  ? 

905.  Who  have  weakened  vision? 

906.  How  are  the  eyes  sometimes  injured? 

907.'  What  is  the  effect  of  protracted  use  of  the  eyes  t 

CHAPTER  XVIII. 

908.  What  does  the  organ  of  hearing  include  ? 

909.  Describe  the  outer  ear. 

910.  What  is  the  natural  position  of  the  ear? 

911.  Should  the  ear  be  covered? 

912.  Describe  the  external  canal. 

913  Describe  the  membrane  of  the  tympanum. 

914  Describe  the  internal  cavity.     The  Eustachian    tube.     What 
oflice  does  this  tube  fulfil  ? 

915,  916.  What  are  within  the  drum? 

917.  What  is  the  auditory  nerve? 

918,  919.  How  is  sound  produced?     What  is  necessary  ? 

920.  How  do  we  know  that  air  is  necessary  ? 

921.  What  is  the  effect  of  unsound  ears  ? 

922.  What  happens  sometimes  to  the  Eustachian  tube? 

923.  924,  925.  What  causes  deafness? 


427 

926    Is  this  faculty  always  the  same? 

927.  What  is  said  of  the  ear  for  .music? 

928.  What  is  man's  responsibility  in  regard  to  his  body?      What  is 
the  consequence  of  violations  of  the  law  ? 

929.  What  relations  exist  among  the  bodily,  intellectual,  and  moral 
powers'? 

930.  What  are  the  intentions  of  nature  in  regard  to  man  ?     Does  he 
realize  them  ? 

931.  What  is  perfect  health? 

932    What  seems  to  be  expected  as  the  common  lot  of  all?     What 
causes  a  greater  loss  than  prostrating  sickness  ? 

933.  What  is  supposed  to  be  the  natural  period  of  human  life?     Is 
this  often  attained?     What  is  the  average  duration  of  life  in  Massa- 
chusetts ?     In  Sweden  ?     In  Russia  ?     Among  different  classes  in  En- 
gland ? 

934.  To  what  conclusions  do  these  facts  lead  us? 

935.  Is  this  abridgment  of  life  owing  to  natural  defects? 

936.  What  are  the  most  common  causes  of  death? 

937.  What  proportion  in  Massachusetts  died  because  the  machinery 
of  life  was  worn  out?     From  what  cause  may  the  premature  failure 
of  one,  or  of  all  the  organs  arise  ? 

938.  How  should  strength  be  added  ?     How  may  a  portion  of  it  be 
expended  ?     How  may  we  err  ? 

939.  What  is  meant  by  the  term  constitution?     To  what  may  it  be 
compared  ? 

940.  How  may  vital  power  be  expended?     When  is  a  sufficiency 
of  vital  power  produced  ? 

941.  How  does  the  system  become  exposed  to  disease?     What  in- 
creases the  danger  of  disease  ? 

942.  What  power  has  man  over  the  varieties  of  constitution  ?    What 
is  the  opinion  of  Thrackrah  ? 

943.  By  what  means  are  we  to  sustain  health  and  prolong  life  ? 


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